Question

求解高数题

Answer 1

=x

方法如下，
请作参考：

Answer 2

这是函数的变形计算，主要步骤如下：
f(x)=(x+1)/(x-1)
则：
f[f(x)]

=[(x+1)/x-1+1]/[(x+1)/(x-1)-1]
=[(x+1)+x-1]/(x-1)/[(x+1-x+1)/(x-1)]
=[2x/(x-1)]/[2/(x-1)
=2x/2
=x.