已知x+1/x=2倍根号2,求x-1/x的值
问题描述:
已知x+1/x=2倍根号2,求x-1/x的值
答
x+1/x=2√2 平方
x^2+2+1/x^2=8
x^2+1/x^2=6
x^2-2+1/x^2=6-2=4
(x-1/x)^2=4
x-1/x=±2