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

Answer Key - Grade 8 Math Worksheet

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

1. 1.

   In math club, Esme meets the line y = 0.5x + 3. What is its slope?

   0.5
2. 2.

   In math club, Jun meets the line y = -x + 9. What is its slope?

   -1
3. 3.

   In math club, Kira meets the line y = -5x − 1. What is its y-intercept?

   -1
4. 4.

   In math club, Luz meets the line y = 9x. What is its y-intercept?

   0
5. 5.

   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
6. 6.

   Ari sketches the line for y = -2x + 5. Which description matches its graph?

   • Crosses the y-axis at 0 and goes down 7 for each 1 across
   • Crosses the y-axis at 5 and goes up 2 for each 1 across
   • Crosses the y-axis at 5 and goes down 2 for each 1 across
   • Crosses the y-axis at -2 and goes up 5 for each 1 across
7. 7.

   Bo graphs y = 2x and then y = 2x + 4. How does the new line compare with the first one?

   • Steeper, through the same point on the y-axis
   • Same steepness, moved 4 to the right
   • Same steepness, moved up 4
   • Same steepness, moved down 4
8. 8.

   Esme graphs y = -3x and then y = -3x − 5. How does the new line compare with the first one?

   • Steeper, through the same point on the y-axis
   • Same steepness, moved down 5
   • Same steepness, moved up 5
   • Same steepness, moved 5 to the left
9. 9.

   Jun graphs y = 0.5x and then y = 0.5x + 3. How does the new line compare with the first one?

   • Same steepness, moved 3 to the right
   • Same steepness, moved up 3
   • Steeper, through the same point on the y-axis
   • Same steepness, moved down 3
10. 10.

    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 takes 8 minutes to drain
    • The bath gains 8 liters each minute
    • The bath loses 8 liters each minute
    • The bath starts with 8 liters