若x+1/x=3,则x方+1/x方=?x方就是x的方.

问题描述:

若x+1/x=3,则x方+1/x方=?x方就是x的方.

x²+1/x²
=x²+1/x²+2-2
=(x+1/x)²-2
=3²-2
=7