(x1-x2)+(1/x1-1/x2)怎样变成(x1-x2)乘以(1-1/(x1x2))又变成((x1-x2)(x1x2-1))/(x1x2)(x1-x2)+(1/x1-1/x2)怎样变成(x1-x2)乘以(1-1/(x1x2))又变成((x1-x2)(x1x2-1))/(x1x2)

Question

(x1-x2)+(1/x1 - 1/x2)怎样变成 (x1-x2)乘以(1- 1/(x1x2))又变成 ((x1-x2)(x1x2-1))/(x1x2)
(x1-x2)+(1/x1 - 1/x2)怎样变成
(x1-x2)乘以(1- 1/(x1x2))又变成
((x1-x2)(x1x2-1))/(x1x2)

Answer 1

后括号内通分：
1/X1-1/X2=(X2-X1)/X1*X2=-(X1-X2)/X1*X2,
前括号与后括号都有因式(X1-X2),提取后,
前括号余下因式1,后括号余下-1/X1*X2,
然后括号内再通分,就是最后结果.
这是分式加减运算的计算过程.