若x=y,则下列等式:①x-1/3=y+1/3;②-3/4x=-3/4y;③1/3x=1/2y;④1-3x=1-3y中,

{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 {3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-1 ｛4/(x+y)+6/(x-y)=3 ｛9/(x-y)-1/(x+y)=1 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 若x=-1/4,能否确定代数式(2x-y)(2x+y)+(2x-y)(y-4x)+2y(y-3x)的值? (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 下列函数：①y=-3x②y=2x-1；③y=-1/x（x 下列函数：①y=-3x；②y=2x-1；③y=-1/x（x [(2x+y)^2+(y+2x)(y-2x)-2y(4x-y)]/4y,其中x=1/2,y=1/3 先化简,再求值：[(x+y)(x-y)-(x-y)^2+2y(x-3y)]/(-4y),其中x=1,y=-2