答案是7将m+1/m=3平方可得m^2+2+1/m^2=9,所以m^2+1/m^2=7
m^2+1/m^2=(m+1/m)^2-2*m*(1/m)=3^2-2=7
m^2+1/m^2=(m+1/m)^2-2M*1/M=3^2-2=7
m^2+1/m^2=(m+1/m)^2-2=3^2-2=7