Question 1053723
{{{f(a)=2a+8}}}
{{{f(a+h)=2(a+h)+8=2a+2h+8}}}
{{{f(a+h)-f(a)=2h+2a+8-2a-8=2h}}}
{{{(f(a+h)-f(a))/h=(2h)/h=2}}}