Question 7492
If f(x) = x^2 + 5, find f(a + h) − f(a)
so f(a) = a^2+5
and f(a+h) = (a+h)^2+5

so f(a + h) − f(a)= (a+h)^2+5-a^2-5
= a^2-h^2+2ah+5-a^2-5
=-h^2+2ah   (Ans)