(1/2x+1/3y)(1/3y-1/2x)+1/2x*(1/2x-1/3y),其中x=4,y=6

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 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 [(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 （2x+y-1)(2x-y+1)-(3x+y)(3x-y),其中x=5分之1, x+y)(x-y)+(x-y)^2-(6x^2y-2xy^2)/2y,其中x=-2,y=1/3 化简求值{(x=2y)(5x-2y)-(3x+2y)(3x-2y)]/4x,其中x=2,y=-1 (X-Y)²+(3X-2Y)(2X+Y)-X(6X-Y),其中X=½,Y=1(先化简再求值) 化简求值：(7x-2y)(3x-2y-1)-(4x+3y)(9x+6y),其中x=2,y=-1 (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 先化简,再求值:(3x-y)²+(3x+y)(3x-y),其中x=1,y=-2