先化解,后求值：（a+1份之1+a-1份之1）÷a²-2a+1份之2a,其中a=2
问题描述：
先化解,后求值：（a+1份之1+a-1份之1）÷a²-2a+1份之2a,其中a=2
答
[1/(a+1)+1/(a-1)]÷2a/(a-1)^2
=2a/(a^2-1)÷2a/(a-1)^2
=2a/(a^2-1)*(a-1)^2/2a
=a-1
=1