Question

Joanne hit a ball straight up into the air. The height of the ball in meters, is given by the function h(t)=-5(t-3)2+45 t seconds after the ball is hit. In how many seconds will the ball hit the ground

Answer 1

6 seconds

Explanation:

The height is zero when ...

0 = -5(t -3)^2 +45

0 = (t -3)^2 -9 . . . . . divide by -5

9 = (t -3)^2 . . . . . . . add 9

±3 = t -3 . . . . . . . . . . square root

3 ±3 = t . . . . . . . . . . .add 3

The height of the ball is zero when t=0 and when t=6.

It will take 6 seconds for the ball to hit the ground.