3x-y=7 4x+2y=163x+4y=18 2x-3y=-5

(x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 2（x+y)-3(x-y)=3 ,4(x+y)+3(x-y)=15 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 （x+y）/2- x-y/2=6 3(x+y)=4(x-y) x+y/3+x-y/2=6 4(x+y)-2(x-y)=40 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 已知（x+y）2 =2,(x-y)3 =3,求(x+y)7(x-y)2(x+y)3(y-x)4 的值 已知实数x.y满足根号(x+y-8)+根号(8-x-y)=根号(3x-y-4)+根号(x-2y+7),求x,y 先化简再求值(x-y)(x-2y)+(x-2y)(x-3y)-2(x-3y)(x-4y) x=4 y=5 计算3x/(x-3y)+(x+y)/(4y-x)-7y/(x-4y)=? (x-y)(x-2y)+(x-2y)(x-7y),其中X=4,Y=1.5 已知2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y