解方程组 2x-y=0 x²-y² 3=

x-y+z=7(1)2x-y-z=0(2)(1)+(2):3x-2y=7(3)x+y=-1y=-1-x将y=-1-x代入3x-2y=7得：3x-2(-1-x)=73x+2+2x=75x=5x=1y=-

楼主自己把第二个代入第一个慢慢算吧,默默飘走.

(x+y)(x-y)-(x+y)=0(x+y)(x-y-1)=0若x-y-1=0y=x-1则4x^2-x^2+2x-1+2x-x+1=03x^2-3x=03x(x-1)=0x=0,x=1y=x-1若x

由(1)得(x+y)(x-y)-2(x+y)=0(x+y)(x-y-2)=0x+y=0x-y-2=0它们与(2)可组成两个方程组x+y=0x-y-2=0x²+xy+y²-28=0x

3x+y=k①x+3y=2②②乘以3,得3x+9y=6③③减去①,得8y=6-ky=(6-k)/8将y=(6-k)/8代入②中,得x+3(6-k)/8=2x=2-3(6-k)/8因为x,y

y=3(x-y),x=2(x-y)x=0y=0再问：请问，怎样解=0，要过程，谢谢再答：y=3(x-y)=3x-3y4y=3xy=3x/4x=2(x-y)=2x-2y=2x-3x/2=x/2x-x/2

2x+3y=12①2x+y=0②①-②得：2y=12,解得,y=6把y=6带入①,2x+18=12,解得,x=-3x+y=7①3（x+y）-7y=7②把②化简得,3x-4y=7③用①乘3-③,得出7y

x^2+xy+y^2+x+5y=0,-----------(1)x+2y=0,x=-2y.代入方程（1）整理后得：y(3y-3)=0,y1=0,x1=0.y2=1,x2=-2.

2x-y=1y=2x-1代入后者得到：x^2-4(2x-1)^2+x+3(2x-1)-1=0x^2-4(4x^2-4x+1)+x+6x-3-1=0x^2-16x^2+16x-4+7x-4=0-15x^

第二个方程化为Y=M+1-2X代入第一个并化为X=（M+3）/3>0得,M>-3,再把第一个化为X=M-1-2Y代入二得Y=（M-3）/3

合并方程组：x+y/2=3x-2y;3x-2y=10+6x+y/4;得出：x=5y/4;从而算出：x=-25/12,y=-5/3.手机打很累.

x-y=a+32x+y=53x=a+8x=(a+8)/3>0a>-8y=-(2a+1)/3-1/2所以a>-1/2

方程2化为：(x+y)²-2xy+(x+y)-32=0代入x+y=7,得49-2xy+7-32=0,得xy=12因此x,y为方程t²-7t+12=0的两个根,解之得t=3,4所以原

｛3x-4y(x-y)=3,2x-3y=12x-3y=1,得x-y=(1+y)/23x-4y(x-y)=3,代入x-y=(1+y)/2,得3x-2y(1+y)=33x-2y-2y²=34y+

x^2-5x-y^2-5y=0(x^2-y^2)-5x-5y=0(x-y)(x+y)-5(x+y)=0(x+y)(x-y-5)=0所以x+y=0,x-y-5=0y=-x或y=x-5若y=x-5代入x^

即(x+y)²=9(x-y-3)(x-y-1)=0所以x+y=3,x-y=1x+y=3,x-y=3x+y=-3,x-y=1x+y=-3,x-y=3所以x=2,y=1x=3,y=0x=-1,y

若3x>y则方程互相矛盾,所以3x＜>y,解得x=9/10,y=21/5

x+y/3=x-y/4⑴2x+3y=11⑵由⑴得x+7y=0,x=-7y(3)将(3)代入⑵得y=-1所以x=7

解方程X=（6+M）/3Y=2M/3-2因为x>0y-6m

展开x^2-2y^2-xy=-5x^2-2y^2+xy=7所以x^2-2y^2=1xy=6上式除以下式,解分式方程x/y=3/2或-4/3(舍去)所以x^2=9y^2=4x=3y=2或x=-3y=-2