\(x^4-27x=x\left(x^3-27\right)=x\left(x-3\right)\left(x^2+3x+9\right)\)
\(27x^5+x^2=x^2\left(27x^3+1\right)=x^2\left[\left(3x\right)^3+1^3\right]=x^2\left(3x+1\right)\left(9x^2-3x+1\right)\)
a) x4-27x=x(x3-27)=x(x-3)(x2-3x+9)
b) 27x5+x2=x2(27x3+1)=x2(3x+1)(9x2-3x+1)