a. f(a) + 3 = ?
(a^2 + 4) + 3 = a^2 + 7
b. f(a + 3) = ?
(a + 3)^2 + 4
a^2 + 9 + 4 = a^2 + 13
c. f(d + b) = ?
(d + b)^2 + 4
d^2 +b^2 + 4 = d^2 +b^2 + 4
