初二7道数学题。把过程写出来！！！数学高手来。

Question

整式乘法
（a+b）²（a-b）²-（a-b）（a+b）（a²+b²）
【2x（x²y-xy）-y（x²-x³y）】÷3x²y
3（y-z）²-（2y+z）（-z+2y）
分式运算

Answer 1

(1).原式=(z+b)(a-b)[(a+b)(a-b)-(a2+b2)]
=(a2-b2)(a2-b2-a2-b2)
=(a2-b2)(-2b2)
=2b2(b2-a2)
(2). 原式=[2x2y(x-1)-x2y(1-xy)]÷3x2y
X2y(2x-2-1+xy)÷3x2y
=2/3x+1/3xy-1
(3).原式=(y-z)2-(4y2-z2)
=y2-2yz+z2-4y2-4y2+4z2
=-3y2+5z2-2yz
① 第一个分母应为a2-b2
原式=a/(a2-b2)-(a-b)/(a+b)(a-b)
=(a-a+b)/(a2-b2)=b/(a2-b2)
(2)原式=2x2/(x-1)-(x+1)(x-1)/(x-1)
(2x2-x2+1)/(x-1)=(x2+1)/(x-1)
(3).=(a+1)/a*(a-1)2/a=(a+1)(a-1)2/a2
(4).=[2x(x-2)/(x+2)(x-2)-x(x+2)/(x2-4)]*(x2-4)/x
=(2x2-2x-x2-2x)/(x2-4)/x=(x2-4x)/x=x-4
(5).=[(x+20/x(x-2)-(x-1)/(x-2)2]÷(x-4)/x
=[(x+2)(x-2)-x(x-1)]/x(x-2)2*x/(x-4)
=(x2-4-x2+x)/x(x-2)2*x/(x-4)
=1/(x-2)2

Answer 2

（a+b）²（a-b）²-（a-b）（a+b）（a²+b²）
=(a+b)(a-b)[(a+b)（a-b)-a2-b2]
=-2(a+b)(a-b)b2
【2x（x²y-xy）-y（x²-x³y）】÷3x²y
=[2x²y(x-1)-x²y(1-x²y)]÷3x²y
=(2x+xy-3)÷3
3（y-z）²-（2y+z）（-z+2y）
= 3y²-6yz+z²-4y²+z²
=-y²-6yz+2z²