解：x1^2+x2^2-x1*x2=21(x1+x2)^2-3x1*x2=21[2(m-2)]^2-3*(m^2+4)=214m^2-16m+16-3m^2-12=21m^2-16m-17=0(m-17)(m+1)=0m=17或者m=-1如有帮助，请给好评谢谢
