college algebra word problem

Question

If f(x) = x^² + 4x + 3, what is f(x + 3)? (Simplify your answer completely.)

Answer 1

substitute x+3 wherever x appears in f(x) to get

f(x+3) = (x+3)^2 + 4(x+3) + 3

= x^2 + 6x + 9 + 4x + 12 + 3

= x^2 +10x + 24

= (x+6)(x+4)