两个分式计算,一个分式解方程,计算：（1）x²-9/x²+2x乘x²-4/x²-3x（2）x²-y²/x÷x²+2xy+

解计算
(1)原式=(x²-9)/(x²+2x) × (x²-4)/(x²-3x)
=(x+3)(x-3)/[x(x+2)] × (x+2)(x-2)/[x(x-3)] 约分
=(x+3)/x × (x-2)/x
=(x+3)(x-2)/x²
(2)原式=(x²-y²)/x ÷ (x²+2xy+y²)/x²
=(x+y)(x-y)/x × x²/(x+y)² 约分
=(x-y) × x/(x+y)
=x(x-y)/(x+y)
解方程：1/(x-1)=1/(x²-1)
方程两边同时乘最简公分母(x²-1)
x+1=1
x=0
检验：把x=0代入最简公分母
x²-1=0-1=-1≠0
x=0是原方程的根

（1）
(x²-9)/(x²+2x)*(x²-4)/(x²-3x)
=[（x-3)(x+3)]/[x(x+2)] *[(x-2)(x+2)]/[x(x-3）]
=(x+3)/x *(x-2)/x
=(x+3)*(x-2)/x²
1/x-1=1/x²-1
1/x=1/x²
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