5x+2y=10 3x-5y=2

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuaihuajian x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 先化简再求值(x-y)(x-2y)+(x-2y)(x-3y)-2(x-3y)(x-4y) x=4 y=5 {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? x-y/7 - x+y/10 =1/2 2(x-y)-5(x+y)=3修改、、、、（x-y)/7-(x+y)/10=1/2 2(x-y)-5(x+y)=3 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 3(2X+Y)+(2(2x-Y)=6 (8X+4y)-(10X-5Y)=2 已知x,y满足约束条件 2x+5y>=10 2x-3y>=-6 2x+y 已知x,y满足约束条件{2x+5y>=10,2x-3y>=-6,2x+y { x-y/7-x+y/10=1/2 {2(x-y)+5(x+y)=3 { x-y/7-x+y/10=1/2 {2(x-y)+5(x+y)=3 (4x-2y-z)-{5x-[8y-2z-(x-2y)]-x-(3y-10z)}=?