如a2-根号22x+1=0,求a-1/a的值

问题描述:

如a2-根号22x+1=0,求a-1/a的值

a2-根号22a+1=0
两边同除以a
a-根号22+1/a=0
所以a+1/a=√22
平方得a²+2+1/a²=22 a²-2+1/a²=18
(a-1/a)²=18
开平方得a-1/a=±3√2