The rocket will be 160 feet high after 3 seconds
Step-by-step explanation:
height = -16t² + 90t + 34
at time = 3 secs
we replace t with 3 secs in the formula above:
height = -16(3)² + 90(3) + 34
height = -16(9) + 270 + 34
Multiplication of same sign gives positive number. Multiplication of opposite signs give negative number.
height = -144 + 270 + 34
height = 160
The rocket will be 160 feet high after 3 seconds