(1)x1+x2+x3=1,(1)x1+2x2-5x3=2,(2)2x1+3x2-4x3=5,(3)(1)+(2)-(3)得0=-2,此方程组无解.(可能是你不小心抄写错误吧!)(2)x1+x2+x3=1x1+2x2-5x3=22x1+3x2-4x2=3
