{6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1
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{6(x-y)-7(x+y)=21{2(x-y)-5(x+y)=-1{6(x-y)-7(x+y)=21{2(x-y)-5(x+y)=-1{6(x-y)-7(x+y)=21{2(x-y)-5(x+y)=
{6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1
{6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1
{6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1
令X-y=a X+y=b
原方程组变为:6a-7b=21,2a-5b=-1 解得:a=7,b=3再X-y=7 x+y=3 得x=5,y=-2
6(x-y)-7(x+y)=21
即x+13y=-21①
2(x-y)-5(x+y)=-1
即3x+7y=1②
①②联立方程组
解得x=5,y=-2
{6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1
若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于
解方程组6(x-y)-7(x+y)=21 2(x-y)-5(x+y)=-1
6(x-y)-7(xy)=21,2(x-y)-5(x+y)=-1
已知:2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x)
x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2
3x+5y-(x+y)=6 2(x+y)-3x=-7
【2(x-y)(x-y)(x-y)-8(x-y)(x-y)(x+y)+6y(x-y)(x-y)]/2(x-y)(x-y)
4.4x+6y=54 9x+2y=87 5.2x+y=7 2x+5y=19 6.x+24.4x+6y=54 9x+2y=87 5.2x+y=7 2x+5y=19 6.x+2y=21 3x+5y=56
【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=
把(x-y)看作一个整体,化解:5(x-y)+2(x-y)-4(x-y)= 3(x-y)把(x-y)看作一个整体,化解:5(x-y)+2(x-y)-4(x-y)=3(x-y)²-4(x-y)+7(x-y)-6(x-y)²=
6(X-Y)-7(x+y)=21
{x+y=7 {2x-5y=-21
若x、y满足2x+y=6,x-3y=1,求7y(x-3y)²-2(3y-x)³的值
求f(x,y)=x+y+7的最大值,使(x,y)满足x+2y≤10,2x+y≥6,y≥0
把(x-y)看做一个整体,合并同类项5(x-y)+2(x-y)-4(x-y)=3(x-y)次方-4(x-y)+7(x-y)-6(x-y)次方=
、1.2x+9y=81 3x+y=341.2x+9y=81 3x+y=34 2.9x+4y=35 8x+3y=30 3.7x+2y=52 7x+4y=62 4.4x+6y=54 9x+2y=87 5.2x+y=7 2x+5y=19 6.x+2y=21 3x+5y=56 7.5x+7y=52 5x+2y=22 8.5x+5y=65 7x+7y=203 9.8x+4y=56 x+4y=21 10.5x+7y=41 5x+8y=44 11.7x+5y=54 3x+4y=38 12.x+8y=15
x+x+y+y+y=21 ,x+x+y+y+y+y+y=27 ,x ,y=?