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8th grade Write y = mx + b from a table, graph or story, and say what m and b mean worksheet

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Write y = mx + b from a table, graph or story, and say what m and b mean

Grade 8 Math Worksheet

NameDate

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

  1. Read this first

    Use the table

    input: xoutput: y
    417
    211
    623
  2. Zee's math-club table shows a line, with no row for x = 0. What rule, written as y = mx + b, gives every row?

  3. Ari's math-club table shows a line, with no row for x = 0. What rule, written as y = mx + b, gives every row?

  4. Bo's math-club table shows a line, with no row for x = 0. What rule, written as y = mx + b, gives every row?

  5. Esme's math-club table shows a line, with no row for x = 0. What rule, written as y = mx + b, gives every row?

  6. Jun draws a line on a math-club grid. Neither marked point is on the y-axis. What rule, written as y = mx + b, gives this line?

  7. Kira draws a line on a math-club grid. Neither marked point is on the y-axis. What rule, written as y = mx + b, gives this line?

  8. Milo's bucket has 4 L of water, and the hose adds 3 L each minute. Let x be minutes and y liters. What rule gives y, as y = mx + b?

  9. Noah's candle is 20 cm tall and burns 2 cm each hour. Let x be hours and y the height in cm. What rule gives y, as y = mx + b?

  10. Pia's plant grows steadily: 9 cm at week 2 and 15 cm at week 5. Let x be weeks and y cm. What rule gives y, as y = mx + b?

  11. Ren's reading log follows y = 12x + 30, the pages read after x days. What does the 12 tell you?

    • Ren reads 12 pages each day
    • Ren reads for 12 days
    • Ren had read 12 pages before day 1
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8th grade Write y = mx + b from a table, graph or story, and say what m and b mean worksheet – printable
Print: 123456

About this worksheet

Write y = mx + b from a table, graph or story, and say what m and b mean. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can write y = mx + b for a line from a table, from two points on a graph, or from a story, even when x = 0 is not shown.
  • I can say what the slope and the y-intercept mean in a story, with their units.
  • I can pick the story that fits a rule such as y = 5x + 20.

Standard: 8.F.B.4

Words to know

rule (equation of the line): y = mx + b: every row of the table obeys it.

slope m: Output change ÷ input change: the change for 1 more x.

y-intercept b: The output at x = 0: the start.

step back: Use the slope to work out the row for x = 0.

initial value: Another name for the start, b.

Common mistakes

Your child put the starting value where the slope goes. In y = 3x + 5, ask: which number is the change for each step, and which is the start?

Your child wrote the rule with only the slope, as if the line went through (0, 0).

Your child used an output from the middle of the table as the start.

What to say

Ask: what is y when x is 0?

Ask: what is y when x is 0?

Questions parents ask

What is the most common mistake with write y = mx + b from a table, graph or story, and say what m and b mean?

Your child put the starting value where the slope goes. In y = 3x + 5, ask: which number is 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.

More grade 8 math

See all grade 8 math

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