Find the average rate of change for the function between the given values.

f(x)=6x^3+4x^2+6; from -5 to -2

Answer: f(x+h)-f(x)/h=3x^2+3xh+8x+4h

I plugged in -2 for x and -3 for h and my result was 11.

Don't know if I am doing this right. Please help.