x/2+y/3=7与2x/3-y/4=1,求它们的二元一次方程组

{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 已知y=y₁+y₂,y₁与x成正比例,y₂与x-1成正比例,且x=3时y=4；x=1时y=2,求y与x之 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= x+y+2(-x-y+1)=3(1-y-x)-4-(y+x-1),x+y=? 2x-5+y/3=x+3y/4+7与10(x-y)-4(1-x)/3-y=0 求方程组的解 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 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 (2x-y)(y+x)-(x-2y)(2y+x)-(-3y+x)^2其(√x+1)+y^2+4=-4y 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 初二数学平面直角坐标系求两条直线交点的坐标:(1)y=-x+7与y=2/3x-4/3(2)y=3x-4与y=-7x+11(3)y=-1/2x+5/2与y=x+2(4)y=1/3(2x+5)与y=1/9(2x+15) 初二上学期方程题 4x+y=5 5x+4y=63x-2y=1 2x+3y=13x-2y=7 7x+5y=32x+3y=17 2x-y=-4x+5y=6 2x+y=23x-6y=4 3x+2y=52x+y=73x-4y=53x+y=1x-2y=-1x+y=42x+3y=92x-3y=74x+5y=3x+y=20004x+6y=90003x+5y=113x-2y=42x+3y=215x-2y=5x+y=54x+3y=182x+3y=16x+4y=132x+3y=40x 已知X和Y满足3X+4Y=2,X-Y-1/7 [(y-2x)(-2x-y)+4(x-2y)平方]/3y,其中x=1,y=-3 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 [(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 x/2+y/3=－3与 7x=8y－4求X、Y,