2x-3y-2=0 5x+3y=18 2x-3y=7 (2x-3y+5)/7+2y=9 2x-3y=3 6x+5y=35

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 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 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 x+y=3 x+2y=9 3/x+1=y y-x=3 y=2x-3 y-3x=1 2(x+1)-y=6 7x-5y=-9 已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= {2x+y/3-2y=0 2(2x+y)-5=7y y-3x=2,y-5x=4,y-7x=6,y-9x=8,y-11x=0方程组, 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 解二元一次方程组:{5(x+y)+3(x-y)=2{7(x+y)-3(x-y)=-6