若｜3X-Y-1｜和2X+Y-4的平方根互为相反数｜3X-Y-1｜＋√﹙2X+Y-4﹚=03x－y－1=0, 2x＋y－4=0解得x=1, y=2X+4Y=1＋8=9X+4Y的算术平方根是3
｜3X-Y-1｜和2X+Y-4的平方根互为相反数3X-Y-1=02X+Y-4=0X=1Y=2X+4Y=1+4*2=9X+4Y的算术平方根=3
