1/2(a+4b)-1/3(3a-6b) ;4a-(a-3b); a+(5a-3b)-(a-2b) ;3(2xy-y)-2xy ;x+[x+(-2x-4y)] 去括号,再合并同类

1/2(a+4b)-1/3(3a-6b) =1/2a+2b-a+2b=-1/2a+4b4a-(a-3b)=4a-a+3b=3a+3ba+(5a-3b)-(a-2b) =a+5a-3b-a+2b=5a-b3(2xy-y)-2xy =6xy-3y-2xy=4xy-3yx+[x+(-2x-4y)] =x+x-2x-4y=-4y