2x-3y=5 5y-3x=6

6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 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 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 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 x+y/2+x-y/3=5/6;x=y/6-x-y/3=1/2 4x-2y-6y*-y-3x+5y* *=2 就是平方 若5x+3y=3x+4y=x+2y+6,则x+y=___ 解二元一次方程组:{5(x+y)+3(x-y)=2{7(x+y)-3(x-y)=-6 已知x,y满足约束条件{2x+5y>=10,2x-3y>=-6,2x+y x+y/2+x-y/3=6,4(x+y)-5(x-y)=2用加减消元法解方程组