(7x-10y)-(-10y-5x)=?

(7x-10y)-(-10y-5x)=? { x-y/7-x+y/10=1/2 {2(x-y)+5(x+y)=3 X+Y=7(100X+Y)-(10Y+X)=(10Y+X)-(10X+Y) 若7x+10y分之5x+y=1/2,则x/y= (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai 2X+Y+Z=10,X+2Y+Z=-6,X+Y+2Z=8 5X+4Y-3Y=13,2X-3Y+7Z=19,3X-Y=2X 1.x+x+x+y+y=6.4 y+y+y+x+x=7.1 x= ( ) y=( ) 2.1,4,7,10,13……这串 5(2x-7y)-(4x-10y)全过程 已知x,y满足约束条件{2x+5y>=10,2x-3y>=-6,2x+y 解方程组:2/(x+y)+5/(x-y)=18 9/(x+y)-10/(y-x)=66 解方程组：2/(x+y)+5/(x-y)=18 9/(x+y)-10/(y-x)=66 10/x+y+3/x-y=-5 15/x+y-2/x-y=-1（用换元法解此方程组）