x = 1

y = 3

Cause, the ball travels 3m in in the first second, right…?

x = 2

y = 3 + (3 + 2) = 8

The ball’s speed for the 2nd second is 5 m/s.

x = 3

y = 3 + (3 + 2) + (3 + 2 + 2) = 15

x = 4

y = 3 + 5 + 7 + 9 = 24

x = 5

y = 24 + 11 = 35

x = 6

y = 35 + 13 = 48

x = 7

y = 48 + 15 = 63

By the 7th second, the ball’s speed is 15 m/s.

x = 8

y = 63 + 15 = 78

x = 9, 10, 11, 12

y = 93, 108, 123, 138

x = 13

y = 138 – 3 = 135

x = 14, 15

y = 132, 129

Then, you can connect all the dots… =)

You can compare the distance from the graph & from the equations. When you get the same answer, then you’re already there…