解:因为关于X的一元两次方程x^2+2(m+1)x+(3m^2+4mn+4n^2+2)=0有实根 所以△=〔2(m+1)〕^2-4(3m^2+4mn+4n^2+2)≥0 4m^2+8m+4-(12 m^2+16mn+16n^2+8) ≥0 4m^2+8m+4-12 m^2-16mn-16n^2-8≥0 合并同类项,整理得 2m^2+4mn-2m+4n^2+1≤0 (m+2n) ^2+(m-1) ^2≤0 m=1 n=-1/2