问一道数学题化简求值题先化简再求值 (a- 2a/a+1 )÷ a的平方-2a+1/a的平方-1 最后再 -a a=5

问题描述:

问一道数学题化简求值题
先化简再求值 (a- 2a/a+1 )÷ a的平方-2a+1/a的平方-1 最后再 -a
a=5

[a- 2a/(a+1 )]÷ (a²-2a+1)/(a²-1) -a
=a(a-1)/(a+1)÷ (a-1)²/(a+1)(a-1)-a
=a(a-1)/(a+1)÷ (a-1)/(a+1)-a
=a-a
=0