The height h(t), of a baseball, in meters, at time t seconds after it is tossed out of a window is

modelled by the function h(t) = −5t

2 + 20t + 15.

a) What is the maximum height that the baseball can reach?
b) At what height is the window?
c) At what time will the ball hit the ground?
d) What is the axis of symmetry of this function?

1 answer

h(t) = −5t^2 + 20t + 15

a) find the vertex by the method you are most comfortable with
in the form (t, h) , h will be your maximum height, t will be the time it happened.

b) clearly, when t = 0, h = 15 <---- the height of the window

c) set -5t^2 + 20t + 15 = 0 , and solve for t. Use the positive result of t

d) it will be the vertical line passing through your vertex, you found that in a)