(1)判别式=(2m-1)^2-4m^2=1-4m≥0,m≤1/4.
(2)x1^2=x2^2则
x1+x2=1-2m=0,或x1=x2,即1-4m=0,所以m=1/2,1/4. 又m≤1/4,所以m=1/4.