问题 解答题

计算:(x-1+y-1)÷(x-1-y-1

答案

(x-1+y-1)÷(x-1-y-1

=(

1
x
+
1
y
)(
1
x
-
1
y

=

y+x
xy
÷
y-x
xy

=

y+x
xy
×
y-x
xy

=

y+x
y-x

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