no es cubo perfecto
27m^3+108m^2 n+144mn^2+64n^3=
x^3-3x^2+3x+1=
125a^3+150a^2 b+60ab^2+8b^3=
(3m+4n)^3
8+36x+54x^2+27x^3=
(5a+2b)^3
(2+3x)^3