已知m^2-7m+1=0,求m^2+1/m^2的值
问题描述:
已知m^2-7m+1=0,求m^2+1/m^2的值
答
m²-7m+1=0
m-7+1/m=0
m+1/m=7
(m+1/m)²=49
m²+1/m²=49-2=47