PROBLEMS INVOLVING MONEY, PROFIT, AND LOSS | Grade 8 Math

Friday, October 24, 2025

PROBLEMS INVOLVING MONEY, PROFIT, AND LOSS

Practice Worksheet: "Mang Larry's Business: Calculating Profit and Loss"

Aligned with the MATATAG Curriculum for Grade 8 Mathematics

Understanding Profit and Loss is simply about knowing whether a business deal made money or lost money. Imagine you buy a toy for ₱100, that is your Cost Price. If you then sell that toy to a friend for ₱150, that selling price is called your Selling Price. Since you sold it for more than you paid, you have made a Profit of ₱50. That's the extra money you get to keep. However, if you had to sell the toy for only ₱80 because it was scratched, then you would have a Loss of ₱20, because you got back less money than you spent. We also calculate percentages to see how big the win or loss is compared to what we originally paid. In short, Profit and Loss is the math that tells you the final score of any business transaction, showing you if you ended up ahead or behind.

Introduction:
This worksheet is designed to help you understand the core concepts of Profit and Loss through real-life situations in the Philippines. Use the formulas below to solve the problems.

Key Formulas:

1. Profit = Selling Price - Cost Price
2. Loss = Cost Price - Selling Price
3. Profit Percentage = (Profit / Cost Price) × 100%
4. Loss Percentage = (Loss / Cost Price) × 100%

Activity: Helping Mang Larry

Mang Larry has a small sari-sari store (neighborhood convenience store) in your barangay. Can you help him calculate his profit or loss on various sales?

Product	Cost Price	Selling Price	Profit or Loss?	Amount	Percentage
1. Rice, 1kg	₱50.00	₱60.00	____________	_______	__________
2. Eggs, one tray	₱150.00	₱140.00	____________	_______	__________
3. Soft drinks, 1.5L	₱85.00	₱100.00	____________	_______	__________
4. Sardines, one can	₱25.00	₱22.00	____________	_______	__________
5. Laundry soap, one bar	₱18.00	₱25.00	____________

Challenge Problem: The Banana Cue Venture

Mang Larry decided to also sell banana cue (caramelized bananas on a stick). The cost to make one batch is ₱25.00 (for bananas, sugar, and charcoal). He sells each stick for ₱15.00. From one batch, he can make 8 sticks.

a) What is the total Selling Price for one batch of banana cue?

Answer: _________________________

b) How much is his profit per batch?

Answer: _________________________

c) What is his profit percentage?

Answer: _________________________

Additional Problems: "Expanding the Business"

Mang Larry's business is growing! Help him with these new financial challenges.

Problem 1: The School Supplies Bundle

For the new school year, Mang Larry created a "School Starter Kit" containing 5 notebooks, 2 pens, and 1 backpack.

ü  Cost: ₱25 per notebook, ₱15 per pen, ₱120 per backpack

ü  Selling Price: ₱35 per notebook, ₱20 per pen, ₱180 per backpack

a) What is the total Cost Price for one bundle?

Answer: Total Cost = (5 × ₱25) + (2 × ₱15) + ₱120 = ______________________

b) What is the total Selling Price for one bundle?

Answer: Total Selling Price = (5 × ₱35) + (2 × ₱20) + ₱180 = ₱175 + ₱40 + ₱180 =  ______________

c) How much profit does he make per bundle?

Answer: Profit = ₱395 - ₱275 = ____________

 

Problem 2: The Cellphone Load

Mang Larry now sells cellphone loads. He buys ₱1,000 worth of load credit for ₱950 from the telecom company. He then sells this load to customers at face value (₱1,000).

a) What is his actual profit from selling ₱1,000 worth of load?

Answer:  Profit = ₱1,000 - ₱950 = _______

b) What is his profit percentage?

Answer:  Profit Percentage = (₱50/₱950) × 100% = _______

Problem 3: The Rice Sack Promotion

Mang Larry bought a 50-kg sack of rice for ₱1,800. He repacks it into 1-kg bags, selling at ₱45 each. However, 2 kg of rice was lost due to spillage during repacking.

a) How much selling price can he actually generate from the rice?

Answer:  Actual rice to sell = 50kg - 2kg = 48kg

             So, Selling Price = 48 × ₱45 = ₱2,160

b) What is his profit or loss?

Answer:  Profit = ₱2,160 - ₱1,800 = _______

c) What is the profit/loss percentage?

Answer:  Profit Percentage = (₱360/₱1,800) × 100% =_______%

Problem 4: The Ukay-Ukay Clothing

Mang Larry started selling second-hand clothes (ukay-ukay). He bought a bundle of 50 pieces for ₱2,000. He plans to sell them at ₱75 each.

a) If he sells all 50 pieces, what will be his total profit?

Answer:  If all sold: Selling Price = 50 × ₱75 = ₱3,750

              So, Profit = ₱3,750 - ₱2,000 = ₱1,750

b) However, 10 pieces remained unsold, and he had to sell them at ₱40 each. What was his actual total profit?

Answer: Actual: 40 pieces at ₱75 = ₱3,000

              10 pieces at ₱40 = ₱400

              Total Selling Price = ₱3,400

              Profit = ₱3,400 - ₱2,000 = ₱1,400

Problem 5: The Fruit Shake Stand

During the summer, Mang Larry sets up a fruit shake stand:

• Cost per shake: ₱12 for fruits, ₱8 for ice/sugar, ₱5 for the cup
• Selling price: ₱35 per shake
• Daily operational cost (rent, electricity): ₱150

a) How much profit does he make per shake?

Answer:  Cost per shake = ₱12 + ₱8 + ₱5 = ₱25. 

                 So,Profit per shake = ₱35 - ₱25 = ₱10 

b) How many shakes must he sell in a day to cover his operational cost?

Answer: Shakes to cover operational cost = ₱150 ÷ ₱10/shake = 15 shakes

c) If he sells 80 shakes in one day, what is his total net profit?

Answer: Gross Profit from shakes = 80 × ₱10 = ₱_____

So, Net Profit = ₱800 - ₱150 = ₱_____

Calculate the missing values in the table below. Use the following formulas:

• Profit = Selling Price - Cost Price
• Loss = Cost Price - Selling Price
• Profit % = (Profit / Cost Price) × 100%
• Loss % = (Loss / Cost Price) × 100%

No. Cost Price        Selling Price           Profit / Loss (Amount)        Profit / Loss (Percentage) 1. ₱100.00 ₱120.00                   ___________________        ___________________ 2. ₱250.00 ₱230.00           ___________________        ___________________ 3. ₱75.00 ₱90.00           ___________________         ___________________ 4. ₱500.00 ₱450.00           ___________________        ___________________ 5. ₱180.00 ₱210.00           ___________________        ___________________ 6. ₱300.00 ₱270.00           ___________________         ___________________ 7. ₱150.00 ₱180.00           ___________________         ___________________ 8. ₱400.00 ₱380.00           ___________________         ___________________ 9. ₱220.00 ₱250.00           ___________________         ___________________ 10. ₱600.00 ₱540.00          Related links Profit and Loss Earning money, profit, and Loss Visitors (please click the line below): Name: _______________________________ Country: _____________________

comments | | Click to Continue...

MATH IS NOT A SUBJECT

Friday, July 18, 2025

 MATH IS NOT A SUBJECT

Do you ever feel like math is just another boring subject you have to study? What if I told you that math isn’t just a subject—it’s a job? And just like any job, you need the right tools and practice to get better at it.

Think about it: A chef needs a knife, a cutting board, and ingredients. A painter needs a brush, a canvas, and colors. And for math? You just need three simple things:

1. A Pen
2. A Paper
3. A Math Problem

That’s it! No fancy gadgets, no complicated setups. Just you, your tools, and the work in front of you.

Why "Work On" Math Instead of "Study" It?

When you study math, it feels like memorizing formulas and rules. But when you work on math, you’re solving puzzles, building skills, and training your brain—just like an athlete trains their body.

• Pen & Paper = Your Gym Equipment

• Math Problems = Your Workout Routine

The more you practice, the stronger you get. And the best part? Every problem you solve makes the next one easier.

How to Treat Math Like a Job and Not a Subject

1. Show Up Daily – Spend at least 15-30 minutes working on problems. Consistency beats cramming!

2. Start Small – Don’t jump into the hardest problems. Build confidence with the easier ones first.

3. Make Mistakes – Messing up is part of the job! Every error is a lesson.

4. Track Progress – Keep a notebook of problems you’ve solved. Seeing improvement is motivating!

Your Math Shift Starts Now!

Grab your pen, paper, and one math problem. Solve it. Then another. And another. Before you know it, you won’t just be studying math—you’ll be working on it like a pro.

Remember: Math isn’t about being perfect. It’s about putting in the work. So clock in, get solving, and watch yourself improve!

Math Is Not Just a Subject—It’s a Job Worth Doing!

Hey there, future problem-solvers and game-changers! 

Let’s be real—when you hear the word "math," what’s the first thing that comes to mind? Boring textbooks? Endless equations? Stressful exams?

What if I told you that math isn’t just a school subject—it’s a job, a superpower, and a daily mission that shapes the world?

Why Math Is More Than Just a Subject

1. Math Is a Skill, Not Just a Grade

Think about it: You don’t just study math—you work on it, like an athlete trains or an artist practices. Nobody becomes a pro basketball player by just reading about it. You do it, fail, adjust, and improve.

Math is the same. Every problem you solve is like leveling up in a video game—the more you practice, the stronger you get!

2. Real-Life Math = Real-Life Jobs

Ever wondered how:

• Game designers create epic worlds? Geometry + Algebra.

• Doctors calculate medicine doses? Fractions + Ratios.

• Engineers build bridges and robots? Calculus + Physics.

Math isn’t just numbers on paper—it’s the secret code behind every cool job. The better you get at it, the more doors open for you!

3. It’s Okay to Struggle—That’s the Job!

Nobody expects you to nail every math problem on the first try. Even geniuses like Einstein had to work hard to figure things out.

Struggle = Growth. Every mistake is just a step closer to mastering it.

How to Treat Math Like a Job (Not Just Homework)

Clock In Daily – Spend at least 15-30 mins practicing (like a daily workout).
Collaborate – Ask friends, teachers, or YouTube tutors for help (teamwork makes the dream work!).
See the Bigger Picture – Connect math to things you love (sports, music, coding, money).

Final Challenge: Be a Math Worker, Not Just a Math Student

Next time you sit down with a math problem, don’t think: "Ugh, another worksheet." Instead, think:

"This is my job. Every problem I solve makes me sharper, smarter, and ready for the future."

Because math isn’t just a subject—it’s your ticket to changing the world. 

Now, go out there and get to work! 

Math Is Not Just a Subject—It’s Your Future Superpower!

Hey, future innovators, creators, and world-changers! 

Let’s cut to the chase: Math isn’t just another class you have to suffer through. It’s not about memorizing formulas or stressing over tests.

Math is a job—your job. And guess what? It’s one of the most powerful jobs in the world.

Why Math Is Your Secret Weapon

1. Math = Brain Gains 

Think of your brain like a muscle. The more you challenge it with math, the stronger and faster it gets.

• Solving problems boosts logical thinking (aka how to outsmart any challenge).

• Math sharpens your creativity (yes, really—ask any coder or engineer!).

• It trains you to never give up—because every mistake is just a step toward the right answer.

Bottom line: Math isn’t just about numbers—it’s about building an unstoppable mind.

2. Every Hero Needs Math (Yes, Even You!) 

Name any dream job—math is there.

• Want to design video games? You’ll use geometry and physics.

• Dream of being a doctor? Dosage calculations = life-saving math.

• Into music or art? Beats, rhythms, and even digital design run on math.

• Love money? Finance, investing, and entrepreneurship are ALL math.

Math isn’t holding you back—it’s launching you forward.

3. The Struggle Is Part of the Job (And That’s Okay!)

Let’s be real: Math can be tough. But so is anything worth mastering.

• Messed up a problem? Good. That means you’re learning.

• Feeling stuck? Ask for help. Even Elon Musk didn’t figure it all out alone.

• Think you’re "not a math person"? Wrong. Math isn’t about talent—it’s about effort.

Pro Tip: The biggest CEOs, scientists, and inventors failed at math before they aced it. You’re in good company.

How to Hack Your Math Job Like a Pro

1. Treat It Like Training, Not Homework

• Small daily reps > last-minute cramming. 15-30 mins a day = huge progress.

• Find the fun. Use apps, games, or real-world challenges (like budgeting or building stuff).

2. Build Your Math Squad

• Study with friends. Teach each other—you learn best by explaining.

• YouTube & TikTok tutors are FREE and make math way cooler than textbooks.

3. Connect Math to Your Dreams

• Love sports? Stats and probability rule the game.

• Into fashion? Patterns, symmetry, and 3D design = math.

• Want to be rich? Learn percentages and investments now.

Your Mission (If You Choose to Accept It)

Next time you open your math book, don’t groan—get excited. Because every equation you solve is:

Sharpening your brain
Prepping you for an epic career
Proving to yourself that you can conquer hard things

Math isn’t just a subject. It’s YOUR superpower. And the world needs what you’re going to do with it. 

Related Articles

comments | | Click to Continue...

Equation of a line Mastery in 3 Steps: Watch, Try, Solve!

Thursday, May 29, 2025

Equation of a Line

1. Introduction 

Hook: Imagine you're designing a roller coaster. Engineers need to calculate the exact slope of each section to ensure a smooth ride. How do they determine the steepness of each track? The answer lies in the equation of a line!

Objective:
By the end of this lesson, you'll be able to:
✔ Write the equation of a line in slope-intercept form (y = mx + b).
✔ Find the slope and y-intercept from a graph or two points.
✔ Convert between different forms of linear equations.

---

2. Prerequisite Knowledge Check

Before we begin, make sure you're familiar with:

1. Plotting points on a graph (Quick Review)

2. Solving for a variable in an equation (Quick Review)

3. Understanding slope (rise over run) (Quick Review)

---

3. Core Concept Explanation (I Do – Teacher Models)

Key Definitions:

• Slope-Intercept Form: y = mx + b

  • m = slope (steepness of the line)

  • b = y-intercept (where the line crosses the y-axis)

Example 1: Writing an Equation from a Graph

📈 Given: A line passes through (0, 2) and has a slope of 3.

✅ Solution:

• b (y-intercept) = 2 (since it crosses the y-axis at 2)

• m (slope) = 3

• Equation: y = 3x + 2

Example 2: Finding Slope from Two Points

📍 Given: Points (1, 5) and (3, 9)

✅ Solution:

• Slope (m) = (9 - 5)/(3 - 1) = 4/2 = 2

• Use one point to find b:

  • 5 = 2(1) + b → b = 3

• Equation: y = 2x + 3

Example 3: Converting to Slope-Intercept Form

📝 Given: 4x + 2y = 8

✅ Solution:

• Solve for y:

  • 2y = -4x + 8

  • y = -2x + 4

---

4. Guided Practice (We Do – Teacher & Students Together)

Let's solve this together:

Problem: Find the equation of a line passing through (2, 8) with a slope of -1.
🔹 Step 1: What's the general form? (y = mx + b)
🔹 Step 2: Plug in the slope (m = -1) → y = -x + b
🔹 Step 3: Use the point (2, 8) → 8 = -(2) + b
🔹 Step 4: Solve for b → b = 10
✅ Final Equation: y = -x + 10

(Try two more examples together! Ask the students to give the point and the slope.)

---

5. Peer Practice (We Do – Students Work Together)

With a partner, solve:

1. Problem: A line passes through (0, -4) with slope 1/2. What's the equation?

   • Hint: Start with y = mx + b and find b.

2. Problem: Find the equation for points (-1, 6) and (1, 2).

   • Hint: First, find slope (m), then b.

3. Problem: Rewrite 3x-y = 5 in slope-intercept form.

   • Hint: Isolate y!

💬 Discuss: Did you and your partner get the same answer?

---

6. Independent Practice (You Do – Students Try Alone)

Try these on your own (solutions at the end):

1. Find the equation of a line with slope 4 and y-intercept -7.

2. A line passes through (3, 10) and (5, 16). Find its equation.

3. Rewrite 5x + 2y = 10 in slope-intercept form.

---

7. Common Mistakes & Troubleshooting

🚨 Watch out for:

• Forgetting to simplify slope (e.g., 6/3 should be 2, not left as a fraction. Reduce to the lowest term.).

• Mixing up x and y when plugging in points.

• Misidentifying the y-intercept (it's where x = 0).

---

8. Real-World Application

Engineers use linear equations to design roads, bridges, and video game graphics! Knowing the slope helps them calculate angles for safety and efficiency.

Economics & Business: Profit Forecasting. Businesses predict profit, set sales targets, and determine break-even points.

Physics: Motion at Constant Speed. Calculates distance traveled over time (e.g., cars, robots, athletes).

Engineering: Hooke’s Law (Springs). Designs springs for machines, scales, or shock absorbers. Ensures springs function safely in products like car suspensions.

Medicine: Drug Dosage Effects. Determines how dosage impacts a patient’s response (e.g., pain relief).

Agriculture: Crop Yield vs. Fertilizer. Optimizes fertilizer use to maximize harvests.

---

9. Summary & Key Takeaways

✨ Remember:

• Slope-intercept form: y = mx + b

• Find the slope (m) using two points or from a graph.

• Y-intercept (b) is where the line crosses the y-axis.

• Always double-check your work by plugging in a point!

---

10. Practice & Extension

Extra Practice:

• Find the equation for a line with slope -2 passing through (4, -3).

• Convert 6x - 3y = 12 to slope-intercept form.

Challenge Question:

• A line passes through (0, 5) and is parallel to y = 2x - 1. What's its equation?

💬 Post your answers below and discuss!

---

Problems on the Slope of a Line

1. Find the slope of the line passing through (2, 5) and (4, 9).
   Solution:
   $m=\frac{9-5}{4-2}=\frac{4}{2}=$ Click to answer

2. Determine the slope of the line passing through (-1, 3) and (5, -7).
   Solution:
   $m=\frac{-7-3}{5-(-1)}=\frac{-10}{6}=$ Click to answer

3. A line has a slope of $\frac{3}{4}$ and passes through (6, -2). Find another point on the line.
   Solution:
   Using $m=\frac{y_2-y_1}{x_2-x_1}$, let $x_2=10$:
   $\frac{3}{4}=\frac{y_2-(-2)}{10-6}$→ $y_2=\; Click\; to\; answer<span\; style="font-family:\; "Times\; New\; Roman";\; font-size:\; medium;\; font-weight:\; 700;"><br></span>$

4. Find the slope of the line $2x+3y=6$.
   Solution:
   Rewrite in slope-intercept form:
   $3y=-2x+6$ → $y=\frac{-2}{3}x+2$ → Slope $m=$Click to answer

5. A line passes through (0, 4) and has a slope of -5. Write its equation.
   Solution:
   Using $y=mx+b$, $b=4$:
   Equation: $y=$ Click to answer

6. Two points on a line are (3, -1) and (7, k). If the slope is 2, find k.
   Solution:
   $2=\frac{k-(-1)}{7-3}$ → $2=\frac{k+1}{4}$ → $k=$ Click to answer

7. Find the slope of a line perpendicular to $y=\frac{2}{5}x-3$.
   Solution:
   Perpendicular slope = negative reciprocal:
   $m_{\perp }=$ Click to answer

8. If a line is horizontal and passes through (4, -2), what is its slope?
   Solution:
   Horizontal lines have slope $m=$Click to answer

9. A line has an undefined slope and passes through (5, -3). Write its equation.
   Solution:
   Lines with undefined slope are vertical:
   Equation: $x=$Click to answer

10. The slope between (a, 8) and (-3, 2) is -2. Find the value of a.
    Solution:
    $-2=\frac{2-8}{-3-a}$ → $-2=\frac{-6}{-3-a}$ → $a=$ Click to answer

_______________________________________________________________________

Practice Problems with Partial Solutions

1. Find the slope of the line passing through (2, 5) and (4, 9).
   Solution:
   $m=\frac{9-5}{4-2}=\frac{4}{2}=2$

2. Determine the slope of the line passing through (-1, 3) and (5, -7).
   Solution:
   $m=\frac{-7-3}{5-(-1)}=\frac{-10}{6}=-\frac{5}{3}$

3. A line has a slope of $\frac{3}{4}$ and passes through (6, -2). Find another point on the line.
   Solution:
   Using $m=\frac{y_2-y_1}{x_2-x_1}$, let $x_2=10$:
   $\frac{3}{4}=\frac{y_2-(-2)}{10-6}$ → $\frac{3}{4}=\frac{y_2+2}{4}$→ $y_2+2=3$ → $y_2=1$
   Another point: $(10,1)$
   

4. Find the slope of the line $2x+3y=6$.
   Solution:
   Rewrite in slope-intercept form:
   $3y=-2x+6$ → $y=-\frac{2}{3}x+2$
   Slope $m=-\frac{2}{3}$

5. A line passes through (0, 4) and has a slope of -5. Write its equation.
   Solution:
   Using $y=mx+b$, $b=4$:
   Equation: $y=-5x+4$
   

6. Two points on a line are (3, -1) and (7, k). If the slope is 2, find k.
   Solution:
   $2=\frac{k-(-1)}{7-3}$ → $2=\frac{k+1}{4}$ → $k+1=8$ → $k=7$.

7. Find the slope of a line perpendicular to $y=\frac{2}{5}x-3$.
   Solution:
   Perpendicular slope = negative reciprocal:
   $m_{\perp }=-\frac{5}{2}$

8. If a line is horizontal and passes through (4, -2), what is its slope?
   Solution:
   Horizontal lines have slope $m=0$
   

9. A line has an undefined slope and passes through (5, -3). Write its equation.
   Solution:
   Lines with undefined slope are vertical:
   Equation: $x=5$
   

10. The slope between (a, 8) and (-3, 2) is -2. Find the value of a.
    Solution:
    $-2=\frac{2-8}{-3-a}$ → $-2=\frac{-6}{-3-a}$
    −2(−3−a)=−6 → $6+2a=-6$
    

11. Further Resources

📚 Learn More:

• Slope of a Line

• Equation of a Line

Next Lesson: Point-Slope Form & Standard Form 🚀

comments | | Click to Continue...

Key Answer to Rectangular Coordinate system

Thursday, May 15, 2025

comments | | Click to Continue...

Plot Like a Pro: Master the Rectangular Coordinate System in Just 5 Steps!

 Understanding Rectangular Coordinate Systems Basics

1. Introduction 

• Imagine this: You're locked in an intense game of Battleship, heart pounding as you call out *"B-5!"* Your opponent hesitates... then groans—direct hit! 🎯 What’s your secret? You’re not just guessing—you’re using math to dominate the grid.

  It turns out that Battleship is really a stealthy lesson in the rectangular coordinate system—the same tool scientists use to map stars, engineers use to design cities, and even your phone uses to navigate. Master this, and you’ll not only crush your opponents in games but unlock the hidden math behind everything from GPS to video game design.

  Ready to turn coordinates into your superpower? Let’s dive in!

• Objective: By the end of this lesson, you will be able to:

  • Plot points accurately on the coordinate plane.

  • Identify the quadrant of a given point.

  • Calculate the distance between two points using the distance formula.

---

2. Prerequisite Knowledge Check

Before diving in, make sure you understand:
✔ Number lines (positive and negative directions).
✔ Ordered pairs (e.g., (3, 4) means x=3, y=4).
✔ Basic operations (addition, subtraction, squaring).

Need a refresher?

• Number Lines Explained

• Ordered Pairs Practice

---

3. Core Concept Explanation

What is the Rectangular Coordinate System?

• A grid formed by two perpendicular number lines:

  • x-axis (horizontal)

  • y-axis (vertical)

• Origin (0,0): Where the axes intersect.

• Quadrants: Four sections labeled I (+,+), II (−,+), III (−,−), IV (+,−).

Common Mistakes to Avoid:

❌ Swapping x and y coordinates (e.g., writing (y, x) instead of (x, y)).
❌ Forgetting negative signs when plotting points (e.g., (−2, 3) vs. (2, 3)).
❌ Misidentifying quadrants (e.g., (3,−5) is in Quadrant IV, not II).

---

4. Worked Examples (Gradual Release of Responsibility)

Example 1 (I Do - Teacher Modeling)

Problem: Plot the point (2, 3).
Solution:

1. Start at the origin (0,0).

2. Move 2 units right along the x-axis (since x=2 is positive).

3. From there, move 3 units up along the y-axis (since y=3 is positive).

4. Mark the point where you land.
   Conclusion: (2, 3) is in Quadrant I.

---

Example 2 (We Do - Guided Practice)

Problem: Plot the point (−1, 4).
Steps Together:

1. Start at (0,0).

2. Move 1 unit left (x=−1).

3. Move 4 units up (y=4).

4. Where is this point located?
   Answer: (−1, 4) is in Quadrant II.

---

Example 3 (You Do Together - Collaborative Practice)

Problem: Identify the quadrant of (−3, −5).
Group Discussion:

• Is x negative or positive? (Negative)

• Is y negative or positive? (Negative)

• Which quadrant has (−,−)?
  Answer: Quadrant III.

---

Example 4 (You Do - Independent Practice)

Problem: Calculate the distance between (1, 2) and (4, 6).
Formula: Distance = √((x₂−x₁)² + (y₂−y₁)²).
Worked Solution:

1. Subtract x-coordinates: 4−1 = 3 → 3² = 9.

2. Subtract y-coordinates: 6−2 = 4 → 4² = 16.

3. Add results: 9 + 16 = 25.

4. Take the square root: √25 = 5.
   Final Answer: The distance is 5 units.

---

Example 5 (Challenge Problem - Extended Thinking)

Problem: Find the distance between (−2, 4) and (3, −1).
Steps:

1. Subtract x-coordinates: 3−(−2) = 5 → 5² = 25.

2. Subtract y-coordinates: −1−4 = −5 → (−5)² = 25.

3. Add results: 25 + 25 = 50.

4. Take the square root: √50 = 5√2.
   Final Answer: The distance is 5√2 units.

---

5. Practice Problems (With Solutions)

Easy: Plot (0, −3). What quadrant is it located in?
Medium: What is the distance between (5, 1) and (2, −3)?
Hard: If point A is (−4, 0) and point B is (0, 3), what is the distance between them?

*Easy: (0,−3) lies on the **y-axis** (not in any quadrant). - 

**Medium: Distance = √((2−5)² + (−3−1)²) = √(9 + 16) = **5 units**. - 

***Hard: Distance = √((0−(−4))² + (3−0)²) = √(16 + 9) = **5 units**. 

---

6. Real-World Applications

• GPS Navigation: Uses coordinates to pinpoint locations.

• Video Games: Characters move based on (x,y) positions.

• Architecture: Blueprints rely on grid systems for precision.

---

7. Summary & Key Takeaways

✔ Points are written as (x, y).
✔ Quadrants are labeled counterclockwise: I → II → III → IV.
✔ Distance formula: √((x₂−x₁)² + (y₂−y₁)²).

 "X comes before Y in the alphabet, just like in (x,y)!"

---

8. Further Reading & Resources

📺 Video: Coordinate Plane
📖 Book: Graphing Notebook
🔗 WOW Math: Math 8

---

9. Interactive Element

Quick Quiz:

1. What quadrant is (−7, −2) in? (Answer: III)

2. What is the distance between (0,0) and (6,8)? (Answer: 10 units)

____________________________________________________________________________

10. Problem set. Fill in the blanks. Given the problems with a partial solution.

🔢 Problem Set: Coordinate Plane Puzzle Fixers

(For small groups of 3-4 students)*

Problem 1: The Misplaced Point

Partial Solution:
*"The point (3, -2) was plotted in Quadrant II, but that’s incorrect because..."*
Task:

1. Identify the error.

2. Correctly plot and label the point.

3. Challenge: Find a point in Quadrant II with the same y-coordinate.

Self-Check: The corrected point forms a rectangle with (-3, -2), (3, -2), and (-3, 2).

---

Problem 2: Distance Detective

Partial Solution:
*"The distance between (1, 4) and (5, 1) is calculated as:
√‾(5−1)² + (1−4)² = √‾16 + ___ = √‾___ = 5 units."*
Task:

1. Fill in the missing steps.

2. Challenge: Find a point on the y-axis that’s exactly 5 units from (1, 4).

Hint: The missing term is a perfect square.

---

Problem 3: Reflection Riddle

Partial Solution:
*"When (2, -3) is reflected over the x-axis, the new point is (2, 3). If you then reflect it over the y-axis, the final point is (___ , ___)."*
Task:

1. Complete the transformation.

2. Challenge: What single reflection would take (2, -3) directly to the final point?

Visual Aid: Provide small mirrors to test predictions.

---

Problem 4: Battleship Logic

Partial Solution:
*"A ship stretches from (-1, 2) to (-1, 5). Its length is 3 units. If another ship runs from (3, -4) to (___, -4) and is twice as long, the missing x-coordinate is ___."*
Task:

1. Find the endpoint.

2. Challenge: Could both ships be sunk by hitting (-1, 4) and (5, -4)? Explain.

Self-Check: The completed ship covers 3 integer x-values.

---

Problem 5: Midpoint Mystery

Partial Solution:
*"The midpoint between (-6, 3) and (2, -1) is:
( (-6 + ___)/2 , (3 + )/2 ) = ( , ___)."*
Task:

1. Fill in the blanks.

2. Challenge: Find the endpoint if (-2, 1) is the midpoint and the other endpoint is (0, 5).

Hint: The missing midpoint coordinates are integers.

---

Problem 6: Shape 

Partial Solution:
"Points A(1, 1), B(1, 4), and C(5, 1) form a right triangle because the slopes of AB and AC are ___ and ___. The area is ___ square units."
Task:

1. Calculate the missing slopes and area.

2. Challenge: Add point D to make a rectangle.

Clue: Area = ½ × base × height.

📝 Practice Problems: Rectangular Coordinate System

Directions: Solve each problem with your group. Show all work and justify your answers.

Basic Skills (Problems 1-3)

1. Plotting Points
   Plot and label these points: A(2, 5), B(-3, 0), C(-1, -4). Identify the quadrant or axis for each.

2. Distance Warm-Up
   Find the distance between (0, 0) and (6, 8).

3. Missing Coordinate
   If (4, y) is 5 units from (1, 2), find *y*. (Hint: There are two possible answers!)

Mid-Level Challenges (Problems 4-6)

4. Quadrant Logic
   "Point P has a negative x-coordinate and a positive y-coordinate. If you reflect P over the y-axis, which quadrant is the new point in?"

5. Perimeter Puzzle
   Three vertices of a rectangle are at (1, 1), (1, 4), and (5, 4). Find:
   a) The fourth vertex.
   b) The perimeter.

6. Collinear Points
   Show whether (2, 3), (4, 6), and (0, 0) lie on the same straight line.

Advanced Applications (Problems 7-10)

7. Battleship Midpoint
   A ship’s midpoint is at (3, 2). One endpoint is (5, 5). Find the other endpoint.

8. Circle Equation
   A circle’s center is at (-1, 3) and passes through (2, 7). Find its radius.

9. Slope Analysis
   A line passes through (-2, 4) and (1, -2). Find:
   a) The slope.
   b) The y-intercept.

10. Real-World GPS
    You’re at (3, -1) and need to reach a café 10 units away at (x, 5). Find *x*.

Worksheet PDF Download

_________________________________________________________________________

🔑 Solutions

1. Plotting Points

   • A(2,5): Quadrant I

   • B(-3,0): On x-axis

   • C(-1,-4): Quadrant III

2. Distance
   √‾(6−0)² + (8−0)² = √‾36 + 64 = √‾100 = 10 units

3. Missing Coordinate
   √‾(4−1)² + (y−2)² = 5 → 9 + (y−2)² = 25 → *y* = 6 or -2

4. Reflection
   Original: Quadrant II → Reflected: Quadrant I

5. Rectangle
   a) Fourth vertex: (5, 1)
   b) Perimeter: 2(4 + 3) = 14 units

6. Collinear Check
   Slope (0,0)→(2,3) = 1.5; Slope (2,3)→(4,6) = 1.5 → Yes, collinear

7. Endpoint
   Midpoint formula → Other endpoint: (1, -1)

8. Radius
   √‾(2−(−1))² + (7−3)² = √‾9 + 16 = 5 units

9. Line Equation
   a) Slope = (−2−4)/(1−(−2)) = -2
   b) y = -2x + 0 → y-intercept: (0, 0)

10. GPS Café
    √‾(x−3)² + (5−(−1))² = 10 → (x−3)² + 36 = 100 → *x* = 11 or -5

_________________________________________________________________________

SIMPLIFIED TIPS FOR LEARNING.

🌟 5 Easy Tips to Master the Rectangular Coordinate System

1. Turn Coordinates into a Game 🎲

• Battleship Method: Play the classic game Battleship (or use graph paper) to practice plotting points like (3,5) and (-2,4).

• Treasure Hunts: Hide "treasure" in your house and describe its location using coordinates (e.g., "3 steps right from the door, 2 steps up").

2. Remember the "X to the Sky, Y to the Thigh" Trick ☝️

• X-axis: Think of it as the ground (left/right).

• Y-axis: Imagine it as a ladder (up/down).

• Quadrants: Use the sign rules:

  • Quadrant I (+, +): Happy (both positive)

  • Quadrant II (−, +): Sad left, happy up

  • Quadrant III (−, −): Sad all around

  • Quadrant IV (+, −): Happy right, sad down

3. Use Real-Life Examples 

• GPS: Google Maps uses coordinates to find locations.

• Sports: Basketball court positions (e.g., (0,0) = center court).

• Art: Pixel art and video game design rely on grids.

4. Master Formulas with Simple Stories 📖

• Distance Formula: Imagine a right triangle between two points. Use the Pythagorean Theorem:

  • "Walk the x-distance (base), climb the y-distance (height), then find the hypotenuse (distance)."
    Example: Distance between (1,2) and (4,6) = √((4-1)² + (6-2)²) = 5 units.

• Midpoint Formula: Think of it as averaging two locations:
  "Add the x’s, divide by 2. Add the y’s, divide by 2. Boom—middle point!"

5. Practice with Mini-Challenges ✏️

• Daily Drills: Plot 3 random points every day and name their quadrants.

• Flashcards: Write point pairs on one side and their distance/midpoint on the back.

• Error Analysis: Intentionally make mistakes (e.g., swap x/y) and correct them.

---

🎯 Pro Tip:

Struggling with negatives? Use colored pens:

• 🔴 Red for negative coordinates

• 🔵 Blue for positive coordinates

Example: (-3, 5) = 3 red steps left, 5 blue steps up.

_______________________________________________________________________

Related Links:

BYJU'S

Desmos

CueMath

Downloadable Practice Problems.

Solutions to Practice Problems

comments | | Click to Continue...