2a^4-a^3-6a^2-a+2

\(2a^4-a^3-6a^2-a+2\\ a^3(2a-1)-[(2a-1)(3a+2)]\\ (2a-1)(a^3-3a-2)\\ (2a-1)(a^3+1-3a-3)\\ (2a-1)[(a+1)(a^2-a+1)-3(a+1)]\\ (2a-1)(a+1)[(a^2-a+1)-3]\\ (2a-1)(a+1)(a^2-a-2)\\ (2a-1)(a+1)(a-2)(a+1)\\\)

I hope this helped,

Gavin.