f(x)=4x-x2. Simplify f(a+h)-f(a)/h

You and your friends are bungee-jumping from an bridge. Let f (x) = -0.0005 x² +1.7 x +4.65, where f(x) represents the height of the bridge's arch above the bottom of the canyon x feet across the bridge. You are standing on a platform 6 feet above the top of the bridge's arch. Your bungee will only stretch 1087 feet. How close will you come to the ground before the bungee retracts? (round your answer to two one decimal place) ft from the bottom 14.85

Find D(f)

For the function f(x)=2x2+x, find f(-5).