A toy rocket was launched from the ground. The function f(x) = -16x^2 + 160x shows the height of the rocket f(x), in feet, from the ground at time x seconds.
x = 10; it takes 10 seconds to reach the maximum height and 10 seconds to fall back to the ground

x = 10; it takes 10 seconds to reach the maximum height and 20 seconds to fall back to the ground

x = 5; it takes 5 seconds to reach the maximum height and 10 seconds to fall back to the ground

x = 5; it takes 5 seconds to reach the maximum height and 5 seconds to fall back to the ground

Question

A toy rocket was launched from the ground. The function f(x) = -16x^2 + 160x shows the height of the rocket f(x), in feet, from the ground at time x seconds.
 x = 10; it takes 10 seconds to reach the maximum height and 10 seconds to fall back to the ground

x = 10; it takes 10 seconds to reach the maximum height and 20 seconds to fall back to the ground

x = 5; it takes 5 seconds to reach the maximum height and 10 seconds to fall back to the ground

x = 5; it takes 5 seconds to reach the maximum height and 5 seconds to fall back to the ground

schrodingers_cat · Answer

Take the derivative and set it equal to zero and solve from the max 

f'x = -32x +160 =0

x = 5

Then to solve from the time for when the ball hits the ground just solve the equation at 0

x(-16x +160) = 0, 10

Hope this helps :)