-8a²-4a²b+2ab=-2a(4a+2ab+b)
8a(x-y)²-4b(y-x)=8a(x-y)²+4b(x-y)=(x-y)(8ax-8ay+4b)第二个还可以写成这样吗：4(y-x)(2ay-2ax-b)，谢谢还有：-4（m+n)2-25（m-2n）2，（ a2+1）2-4a（a2+1）+4a2-4（m+n)²-25（m-2n)²=-[4(m+n)²+25(m-2n)²]=-[4m²+8mn+4n²+25m²-100mn+100n²]=-[29m²-92mn+104n²] ( a²+1）²-4a（a²+1）+4a²=(a²+1)²-4a(a²+1)+(2a)²=(a²-2a+1)²=[(a-1)²]²=(a-1)^4