已知x=-1,y=2和x=2,y=-3是方程mx+ny=1d的解,求3m+7的值

已知X和Y满足3X+4Y=2,X-Y-1/7 已知X,Y,满足(X+3Y)(X-3Y)=-10(Y^2-6/5)和2X(Y-1)+4(1/2X-1)=0 （X+Y)^2 X^2Y+XY^2注：*/* 是分数 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知x和y满足3x+4y=2,x-y 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 已知x-y=-3y+5,则式子x+2y-1的值是? 已知1/x+2=y-3/y-4,用x的代数式表示y是 已知x-y=1,求[(x+2y)^2+(2x+y)(x-4y)-3(x+y)(x-y)]除以y的值大神们帮帮忙 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² 已知x是实数,y是虚数,且满足(2x-1)+i=y-(3-y)i,求x和y 已知x-2y/3y-x=2/3,则y/x的值是 已知实数x,y满足y=|x-1|,则x+2y的最大值是 已知|x|=2,|y|=3,|x+y|=-(x+y)求x-y 已知x^2-2=y,则x(x-3y)+y(3x-1)-2的值是, 已知1/x-1/y=1/x-y则2y/x+2x/y的值是 已知x+y=a,2x-y=-2a,求[（x/y-y/x)/(x+y)-x(1/x-1/y)]/[(x+1)/y]的值