&*** (20 9:44:5)
问题描述：
&*** (20 9:44:5)
1／χ+χ=3,则χ4+χ²+1／χ²=?
答
(x^4+x^2+1)/x^2
=x^2 +1/x^2 +1
=x^2 +1/x^2+2 -1
=(x+ 1/x)^2-1
=3^2-1
=8