{7x—2y=3,9x+2y=-19 急.
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
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
x-2y=9 x+y+z=7 2x-3y=12
用消元法求2x+3y=0、3x+5y=—1(急,
先化简,再求值:x-3(x+2y)+4(2y-x),其中x=-3,y=2 急
【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=
方程组求解:x-2分之1y=1 2x+3y=8 3x-2y=9 x+2y=3 2y=7x+3 9x+2y=19
化简求值:(7x-2y)(3x-2y-1)-(4x+3y)(9x+6y),其中x=2,y=-1
3x+2=y 5X+4=Y 7X+6=Y 9X+8=y 11x=y要如何计算
3x+2=y 5x+4=y 7x+6=y 9x+8=y 11x=y