It's just a matter of plugging in what's in the parentheses of f( ) for x. Suppose f(x)=4x-4. f(-2)= You just plug in -2 for x in f(x)=4x-4. f(-2)=4(-2)-4 = -8-4 = -12 ------------------- f(x)+f(-2)= You just plug in (4x-4) for f(x) and (-12) for f(-2) f(x)+f(-2)= (4x-4)+(-12) = 4x-4-12 = 4x-16 Edwin