4p^3 + 20p^2 - 45 = 9p

4p^3 + 20p^2 - 9p - 45 = 0

4p^2(p+5) - 9(p+5) = 0
(4p^2-9)(p+5) = 0
(2p+3)(2p-3)(p+5) = 0