当x=3,y=4,x的-2方+y的-2方=
问题描述:
当x=3,y=4,x的-2方+y的-2方=
答
解
x^(-2)+y^(-2)
=1/x²+1/y²
=1/3²+1/4²
=1/9+1/16
=(25)/144