干什么?計算嗎?
原式=x/y
(x²-y²)/(xy)-(xy-y²)/(xy-x²)
=(x²-y²)/(xy)-y(x-y)/[x(y-x)]
=(x+y)(x-y)/(xy)+y(x-y)/[x(x-y)]
=[(x-y)/x][(x+y)/y+y/(x-y)]
=[(x-y)/x][(x+y)(x-y)+y²]/[y(x-y)]
=[(x-y)/x](x²-y²+y²)/[y(x-y)]
=[(x-y)/x]{x²/[y(x-y)]}
=[(x-y)x²]/[xy(x-y)]
=x/y
為了滿足樓主“要過程‘的要求,是樓主看清楚解題思路,上邊寫得比較啰嗦.