分解因式：(a²-a+2)(a²-6a+2)+6a²
原式=a⁴-a³+2a²-6a³+6a²-12a+2a²-2a+4+6a²
=a⁴-7a³+16a²-14a+4=a³(a-1)-6a²(a-1)+10a(a-1)-4(a-1)
=(a-1)(a³-6a²+10a-4)=(a-1)[a²(a-2)-4a(a-2)+2(a-2)]
=(a-1)(a-2)(a²-4a+2)