find the difference quotient for f(x)=-2x^2+5x

Answer 1

(f(x+h) -f(x))/(x+h-x)

= (-2(x+h)^2 +5(x+h)- -(2x^2 +5x))/h

= (-4xh-2h^2+5h)/h

= -4x-2h+5

which = -4x +5 = f'(x)=the derivative when h =0