已知m+1/m=4求m^2+1/m^2的值.(请写出计算过程)

问题描述:

已知m+1/m=4求m^2+1/m^2的值.(请写出计算过程)

m+1/m=4
两边同乘M,得m^2-3m=0
m只能为正三
将m=3代入m^2+1/m^2得82/9

解:m+(1/m)=4
[m+(1/m)]^2=m^2+(1/m)^2+2=16
m^2+(1/m)^2=14

m^2+1/m^2=(m+1/m)^2-2m*(1/m)=16-2=14

(m+1/m)^2=m^2+1/m^2+2=16
m^2+1/m^2=14