当a=1/√3+2时,求（a²-a-6）/(a+2)-√（a²-2a+1）/(a²-a)的值.

当a=1/√3+2时,求（a²-a-6）/(a+2)-√（a²-2a+1）/(a²-a)的值.
当a=1/√3+2时,求（a²-a-6）/(a+2)-√（a²-2a+1）/(a²-a)的值.

当a=1/√3+2时,求（a²-a-6）/(a+2)-√（a²-2a+1）/(a²-a)的值.
a=1/(√3+2)
=(2-√3)/(√3+2)(2-√3)
=(2-√3)/(4-3)
=2-√3
a-1=1-√3