(2m+3)^2-4m^2>=0 12m+9>0 m>-3/4 1/m^2=1 m=1 x^2+（a+1）x+2a+1=0 0<-2(a+1)/2<2 -2-34(a+1)^2-4(2a+1)>=0 4a^2+8a+4-8a-4>=0 a^2>=0 所以，-3a=-2
