3/2 x+3/1 y=1.5x,解得y∶x=5∶2.

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-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 十万分,[3x+2y]/2=[2x+y]/3=[x-y+1]/4 解得. (1)x+y=15 (2)5x-2（10-x）=6y-3（10-y）+19 解得x=9 数学题……555{(3x+y)(3x-y)-(x-5y)(5x-y)-(x-2y)²÷(-4x),x=-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)+...-( 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 解方程组{(x-2)(y+3)=(x+1)(y-1) {(x+1)(y+1)=(x-1)(y+5) （2x+y-1)(2x-y+1)-(3x+y)(3x-y),其中x=5分之1, 将3x-y=7和2x+y=8组成方程组得，3x-y=72x+y=8，解得， 若x-2y=5,则式子12-x+2y=.以知3x-4y=2x+y则x∶y= (3x-y)^2+(3x+y)(3x-y),x=1,y=-2