(-2根号2)平方-（根号2+1）平方+（根号2-1）负一次方
=8-（3+2√2）+[1/(√2-1)]
=5-2√2+√2+1
=6-√2您的第2步+[1/(√2-1)]到第3不√2+1的分之1怎么没有了？请赐教谢谢分子分母同乘（√2+1）1/(√2-1)=（√2+1）/（√2-1）（√2+1）=（√2+1）/（2-1）=√2+1