Answer:
y = 80 ft
Step-by-step explanation:
The height will be maximum at the point where the derivative of y with respect to x becomes  zero. So, first we will take derivative of the equation with respect to x:
dy/dx = (d/dx)(-16 x² + 32 x + 80)
dy/dx = -32 x + 32
Now, we set it equal to zero:
dy/dx = 0 = - 32 x + 32
32 x = 32
x = 32/32
x = 1
Therefore, height will be maximum at x = 1. So, we put x = 1 in equation:
y = -32(1)² + 32(1) + 80
y = 80 ft
