x^2+1/x^2=7,x+1/x等于
问题描述:
x^2+1/x^2=7,x+1/x等于
答
(x+1/x)²
=x²+2+1/x²
=7+2
=9
所以x+1/x=±3
x^2+1/x^2=7,x+1/x等于
(x+1/x)²
=x²+2+1/x²
=7+2
=9
所以x+1/x=±3