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

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Answer 1 · 2016-06-16T12:06:10

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

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

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

How do you factor 27a^4 - a27a^4 - a?