given the function fx84x2 a fa 84a2 b fah 84a28ah4h2 c find

given the function, f(x)=8+4x^2,

a.) f(a)= 8+4a^2

b) f(a+h)= 8+4a^2+8ah+4h^2

c.) find (f(a+h)-f(a)) / h

I got part A and B right and I tried C and got 8ah+4h but that is incorrect.

f(x) = 8 +4x^2

f(a)= 8+4a^2

f(a+h)= 8+4a^2+8ah+4h^2

[ f(a+h) - f(a)]/h

= [ 8+4a^2+8ah+4h^2 - 8 -4a^2]/h

= (8ah +4h^2)/h

h gets cancelled from num erator and denominator

= 8a + 4h