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

Answer Key - Grade 8 Math Worksheet

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

1. Read this first

   Use the table

   input: x	output: y
   4	17
   2	11
   6	23

2. 1.

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

   y = 3x + 5
3. 2.

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

   y = 3x − 5
4. 3.

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

   y = -2x + 5
5. 4.

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

   y = 2x ÷ 3 + 2
6. 5.

   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?

   y = -2x + 3
7. 6.

   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?

   y = 3x + 4
8. 7.

   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?

   y = -2x + 20
9. 8.

   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 had read 12 pages before day 1
   • Ren reads for 12 days
10. 9.

    Tala's snowman follows y = -4x + 50, its height in cm after x hours of sun. What does the 50 tell you?

    • The snowman melts 50 cm each hour from the start
    • The snowman was 50 cm tall at hour 0
    • The snowman melts after 50 hours of sun
11. 10.

    Zee's class fund follows y = 2.5x + 10, the dollars after x weeks. What does the 2.5 tell you?

    • The fund grows by $2.50 each week
    • The fund has $2.50 now
    • The fund started with $2.50