Grade 8 · Math

8th grade Read the slope and y-intercept from y = mx + b worksheet

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Read the slope and y-intercept from y = mx + b

Grade 8 Math Worksheet

NameDate

Circle the best answer, or write your answer on the line.

In math club, Bo meets the line y = -2x − 7. What is its slope?
In math club, Kira meets the line y = -5x − 1. What is its y-intercept?
In math club, Luz meets the line y = 9x. What is its y-intercept?
In math club, Milo meets the line y = -3x + 12. What is its y-intercept?
Noah graphs y = 4x + 6. At what point does the line cross the y-axis? Write it as (x, y).
Pia graphs y = -2x − 3. At what point does the line cross the y-axis? Write it as (x, y).
Ren graphs y = x − 7. At what point does the line cross the y-axis? Write it as (x, y).
8.
Zee sketches the line for y = 3x − 4. Which description matches its graph?
- Crosses the y-axis at -4 and goes up 3 for each 1 across
- Crosses the y-axis at 4 and goes up 3 for each 1 across
- Crosses the y-axis at 3 and goes down 4 for each 1 across
9.
Luz's bath drains following L = 40 − 8m, with L the liters left after m minutes. What does the -8 in the rule tell you?
- The bath starts with 8 liters
- The bath takes 8 minutes to drain
- The bath gains 8 liters each minute
- The bath loses 8 liters each minute
10.
Milo's class fund follows d = 3w + 20, with d the dollars after w weeks. What does the 3 tell?
- The fund has $3 now
- The fund started with $3
- The fund grows by $3 each week

Read the slope and y-intercept from y = mx + b. Every version has 10 questions, and the answer key prints on the second page.

I can read the slope m and the y-intercept b from y = mx + b, keeping their signs, and write where the line crosses the y-axis as (0, b).
I can first rewrite a rule such as y = 5 + 3x, y = 6(x + 7), 2y = 8x + 6 or y − 4 = 2x as y = mx + b.

Standard: 8.EE.B.6 (y = mx + b part), 8.F.A.3

slope (m): The number multiplying x: how much y changes for each 1 of x.

y-intercept (b): The number alone: the output when x = 0, where the line crosses the y-axis.

slope-intercept form: A rule written y = mx + b, with y alone on one side.

y-axis: The up-and-down axis, where x = 0.

slide (translate): Move a line up or down without turning it.

Your child mixed up the slope and the y-intercept. In y = 3x + 5, ask: which number goes with x (the change for each step), and which is the start?

Your child read the right number but left off its minus sign.

Your child thought a rule like y = x + 6 has slope 0 because no number is written in front of x.

Ask: is the number added or taken away in the rule?

Ask: what is 1 times x?

What is the most common mistake with read the slope and y-intercept from y = mx + b?

Your child mixed up the slope and the y-intercept. In y = 3x + 5, ask: which number goes with x (the change for each step), and which is the start?

Are these 8th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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