已知A=2x-3xy+y-x+2y,B=4x-6xy+2y-y,若|x-3a|+(y+5)=0,且B-2A=a,
问题描述:
已知A=2x-3xy+y-x+2y,B=4x-6xy+2y-y,若|x-3a|+(y+5)=0,且B-2A=a,
答
若|x-3a|+(y+5)=0,则x=3a,y=-5; B-2A=4x-6xy+2y-y-2(2x-3xy+y-x+2y)=4x-6xy+2y-y-4x+6xy-2y+2x-4y=2x-5y=6a+25 6a+25=a,-5a=25,a=-5