Answer: (x+5)(x+2)^2
Step-by-step explanation: Expanding (x+5)(x+4)(x+4) gives:
(x+5)(x+4)(x+4) = x(x+4)(x+4) + 5(x+4)(x+4)
= x^2(x+4) + 4x(x+4) + 5x(x+4) + 20(x+4)
= x^3 + 4x^2 + 5x^2 + 20x + 16x^2 + 80x + 20x + 80
= x^3 + 9x^2 + 45x + 80
Fully simplifying this expression gives:
x^3 + 9x^2 + 45x + 80 = (x+5)(x^2+4x+16)
= (x+5)(x+2)^2