Let f(x)+10x^2+9x+10. Find f(x+h)-f(x).

10(x+h)^2+9(x+h)+10-(10x^2+9x+10)

10(x^2+xh+h^2)+9x+9h+10-10x^2-9x-10
10x^2+10xh+10h^2+9h-10x^2
10xh+10h^2+9h