Let's solve the problem step-by-step using the information provided in the image. The goal is to
write linear equations from a table using the
slope-intercept form:
$$
y = mx + b
$$
where:
- $ m $ is the
slope
- $ b $ is the
y-intercept
---
🔹 Step 1: Understand the Steps
The worksheet gives two cases:
####
✔ Case 1: If $ x = 0 $ is in the table
1. Find the slope from the table.
2. Identify the y-intercept (the $ y $ value when $ x = 0 $).
3. Substitute
slope ($ m $) and
y-int ($ b $) into $ y = mx + b $.
####
✘ Case 2: If $ x = 0 $ is NOT in the table
1. Find the slope.
2.
Substitute your $ x $ and $ y $ values into the equation.
3. Substitute the
slope and the
point into $ y = mx + b $.
4. Solve for $ b $.
5. Write the equation with $ m $ and $ b $.
---
Now let’s go through each
example and fill in the blanks.
---
## 🟦 Example 1: Table with $ x = 0 $
| x | -1 | 0 | 1 | 2 |
|---|----|---|---|---|
| y | 0 | 2 | 4 | 6 |
Step 1: Find the slope $ m $
Use two points: say $ (-1, 0) $ and $ (0, 2) $
$$
m = \frac{\Delta y}{\Delta x} = \frac{2 - 0}{0 - (-1)} = \frac{2}{1} = 2
$$
✔ Slope $ m = 2 $
Step 2: Find y-intercept $ b $
When $ x = 0 $, $ y = 2 $ → So $ b = 2 $
Step 3: Write equation
$$
y = mx + b = 2x + 2
$$
✔ Final answer: $ y = 2x + 2 $
---
## 🟦 Example 2: Table with $ x = 0 $
| x | -2 | 0 | 2 | 4 |
|---|----|---|---|---|
| y | 5 |10 |15 |20 |
Step 1: Find the slope $ m $
Use $ (0, 10) $ and $ (2, 15) $
$$
m = \frac{15 - 10}{2 - 0} = \frac{5}{2} = 2.5
$$
Or as fraction: $ \frac{5}{2} $
✔ Slope $ m = \frac{5}{2} $
Step 2: Y-intercept $ b $
When $ x = 0 $, $ y = 10 $ → $ b = 10 $
Step 3: Equation
$$
y = \frac{5}{2}x + 10
$$
✔ Final answer: $ y = \frac{5}{2}x + 10 $
---
## 🟦 Example 3: Table without $ x = 0 $
| x | 3 | 6 | 12 | 15 |
|---|----|----|----|----|
| y | 20 | 16 | 8 | 4 |
We need to find the slope first.
Step 1: Find slope $ m $
Use two points: $ (3, 20) $ and $ (6, 16) $
$$
m = \frac{16 - 20}{6 - 3} = \frac{-4}{3} = -\frac{4}{3}
$$
✔ Slope $ m = -\frac{4}{3} $
Step 2: Pick a point to substitute
Let’s use $ (3, 20) $
So we plug into:
$$
y = mx + b
$$
$$
20 = -\frac{4}{3}(3) + b
$$
$$
20 = -4 + b
$$
$$
b = 24
$$
✔ $ b = 24 $
Step 3: Write equation
$$
y = -\frac{4}{3}x + 24
$$
✔ Final answer: $ y = -\frac{4}{3}x + 24 $
---
✔ Summary of Filled-in Worksheet:
#### Example 1:
- Slope: $ m = \frac{\Delta y}{\Delta x} = \frac{2 - 0}{0 - (-1)} = \frac{2}{1} = 2 $
- Y-int: $ b = 2 $
- Equation: $ y = 2x + 2 $
#### Example 2:
- Slope: $ m = \frac{15 - 10}{2 - 0} = \frac{5}{2} $
- Y-int: $ b = 10 $
- Equation: $ y = \frac{5}{2}x + 10 $
#### Example 3:
- Slope: $ m = \frac{16 - 20}{6 - 3} = \frac{-4}{3} $
- Point: $ (3, 20) $
- Plug in:
$$
20 = -\frac{4}{3}(3) + b \Rightarrow 20 = -4 + b \Rightarrow b = 24
$$
- Equation: $ y = -\frac{4}{3}x + 24 $
---
🔁 Final Answers:
#### Example 1:
$$
y = 2x + 2
$$
#### Example 2:
$$
y = \frac{5}{2}x + 10
$$
#### Example 3:
$$
y = -\frac{4}{3}x + 24
$$
---
✔ Key Takeaways:
- Always calculate slope using $ m = \frac{\Delta y}{\Delta x} $
- If $ x = 0 $ is in the table, read $ b $ directly.
- If not, pick any point, plug into $ y = mx + b $, and solve for $ b $.
- Then write the final equation.
Let me know if you'd like this printed or formatted for study!
Parent Tip: Review the logic above to help your child master the concept of writing equations from tables and graphs worksheet.