Question 43372
{{{f(x)= x^2 + 5}}}


So, when x = a replace 'x' by 'a'
then, {{{f(a)= a^2 + 5}}}


Also, when x = (a+h) replace 'x' by (a+h)
then, {{{f(a+h)= (a+h)^2 + 5}}}
or {{{f(a+h)= (a+h)^2 + 5}}}


{{{f(a+h) - f(a) = ((a+h)^2 + 5) - (a^2 + 5)}}}
or {{{f(a+h) - f(a) = a^2 + 2ah + h^2 + 5 - a^2 - 5}}}
or {{{f(a+h) - f(a) = 2ah + h^2}}}


So your answer is incorrect.