x1+x2=m+1x1x2=m+2所以x1²+x2²=(x1+x2)²-2x1x2=m²+2m+1-2m-4=6m²=9m=±3有解则△=m²+2m+1-4m-8>=0m²-2m-7>=0所以m=-3
设两根x1,x2x1+x2=m+1x1x2=m+2x1^2+x2^2=(x1+x2)^2-2x1x2=(m+1)^2-2(m+2)=m^2-3=6m^2=9m=±3
正负3
