Question 1065612
{{{f(a)=a^2-7a+4}}}
{{{f(a+h)=(a+h)^2-7(a+h)+4=a^2+2ah+h^2-7a-7h+4=a^2+(2h-7)a+h^2-7h+4}}}
So then,
{{{f(a+h)-f(a)=a^2+(2h-7)a+h^2-7h+4-(a^2-7a+4)}}}
{{{f(a+h)-f(a)=2ha+h^2-7h}}}
{{{f(a+h)-f(a)=h(2a-7)+h^2}}}