作业帮2x-y=6,5x+2y=-21
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2x-y=6,5x+2y=-21
2x-y=6,5x+2y=-21
2x-y=6,5x+2y=-21
2x-y=6
4x-2y=12 ①
5x+2y=-21 ②
①+②得9x=-9
所以x=-1
将x=-1代入2x-y=6
解得y=-8
【答案】x=-1 y=-8
2x-y=6
所以4x-2y=12
与5x+2y=-21相加
9x=-9
x=-1
2x-y=6
y=2x-6=-2-6=-8
2x-y=6(1),5x+2y=-21(2)
由（1）得：y=2x-6(3)
把（3）代入（2）得
5x+2（2x-6）=-21
解得x=-1，y=-8
{6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1
x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2
x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2
6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5
解方程组6(x-y)-7(x+y)=21 2(x-y)-5(x+y)=-1
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
6（x-y)-7(xy)=21,2(x-y)-5(x+y)=-1
【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=
X^2-Y^2+6X+10Y-30=0 X^2+Y^2-5X-8Y+21=0 X=?Y=?
3x+5y-(x+y)=6 2(x+y)-3x=-7
2(x-y)=5y,x-y=-5
（x+y）/2- x-y/2=6 3(x+y)=4(x-y)
x+y/3+x-y/2=6 4(x+y)-2(x-y)=40
x-y / 5y= (y-x)^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=
[(2x-y)(2x+y)+y(y-6x)]÷2x=?
解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7
3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2