计算1/x-1/x-4
问题描述：
计算1/x-1/x-4
答
1/x -1/(x-4)
=(x-4-x)/x(x-4)
=4/x(4-x)
计算1/x-1/x-4
1/x -1/(x-4)
=(x-4-x)/x(x-4)
=4/x(4-x)