Question

How do you factor `27a^4 - a`?

Answer 1

`a(3a-1)(9a^2+3a+1).`

Explanation:

Formula : `x^3-y^3=(x-y)(x^2+xy+y^2).`

Expression `=27a^4-a=a(27a^3-1)=a{(3a)^3-1^3}=a(3a-1){(3a)^2+3a*1+1^2}=a(3a-1)(9a^2+3a+1).`