(m²+n²)(m²+1+n²)=6(m²+n²)(m²+n²+1)=6（m^2+n^2）^2+(m^2+n^2)-6=.0(m^2+n^2+3)(m^2+n^2-2)=0所以,m^2+n^2+3=0 m^2+n^2-2=0m²+n²≥0m^2+n^2=-3(舍去） m^2+n^2=...