若x+1/x=3,则x2+1/x2的值.
问题描述:
若x+
=3,则x2+1 x
的值. 1 x2
答
x+
=31 x
(x+
)2=321 x
x2+2×x×
+1 x
=91 x2
x2+
=9-21 x2
x2+
=7.1 x2