For the function f(x)=-2x^2:
(a) A simplified form of the difference quotient (f(x+h)-f(x))/h, when h!=0, is .
(b) Use the simplified form to compute the difference quotient for the following.
When x=2 and h=1, the difference quotient is .
When x=2 and h=0.2, the difference quotient is .
When x=2 and h=0.1, the difference quotient is .
When x=2 and h=0.01, the difference quotient is .