......_________________________________________________............2xlnx-x^2+ax-3aA.（-0）B.（-4]C.（0+）D.[4+）lnxx12*1*0-1+a-3a4Bax+2lnx+3xx0y=x+2lnx+3xy=（x^2+2x-3）x^2y=0x1=-3x2=1x（01）x（1+）x=1y4a4B4