please help me!! :(

Question

On a windy morning, a hot air balloon starts rising and flying away from the top of a hill. The altitude, h, in feet, of the balloon x hours after starting its ascent from the hill, can be modeled by this function:

h(x) = –16x2 + 64x + 80.

?/1

How many hours have passed when the hot air balloon lands on the ground?

Answer 1

h(x) = 0

0 = -16x² + 64x + 80

0 = x² - 4x + 5

0 = (x - 5)(x + 1)