1、(x-1分之x²)-x-1（因式分解）；2、x²(x-y)²-4(y-x)²

1、x²/(x-1) -(x+1)(x-1)/(x-1)=[x²-(x+1)(x-1)]/(x-1)=1/(x-1)2、=x²(x-y)-4(x-y)²=(x-y)²(x²-4）=(x-y)²(x+2)(x-2)3、=(a+1)/a× 4a²/(a+1)²-1/(a-1)+1/(a+1)=4a/(a+1)+1/(a+1)-1/(a-1)=(4a+1)/(a+1) -1/(a-1)=[(4a+1)(a-1)-(a+1)]/(a+1)(a-1)=(4a²-4a-2)/(a²-1)