F(x) = x^2 +3x + 5. For f( 3+h), put x = 3+h. F( 3+h)= (3+h) ^2 + 3 (3+h) +5 = 9 +h^2 + 6h + 9 + 3h + 5 = h^2 + 9h + 23. .
