5x+2y=10 2x+5y=8
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5x+2y=102x+5y=85x+2y=102x+5y=85x+2y=102x+5y=85x+2y=10(1)2x+5y=8(2)(1)+(2)7x+7y=18x+y=18/7则2x+2y=36/7
5x+2y=10 2x+5y=8
5x+2y=10 2x+5y=8
5x+2y=10 2x+5y=8
5x+2y=10 (1)
2x+5y=8 (2)
(1)+(2)
7x+7y=18
x+y=18/7
则2x+2y=36/7 (3)
(1)-(3)
3x=34/7
所以x=34/21
y=18/7-34/21=20/21
①式左右同乘2得：2(5x+2y)=20,③
②式左右同乘5得：5(2x+5y)=40,④
④-③得：25y-4y=40-20,21y=20
y=20/21
y值带入①式求得：x=34/21
(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuaihuajian
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
3(2X+Y)+(2(2x-Y)=6 (8X+4y)-(10X-5Y)=2
(4x-2y-z)-{5x-[8y-2z-(x-2y)]-x-(3y-10z)}=?
x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2
3x-2y=9 x-3y=2 x+y=5 x+2y=3 y=x 2x+y=8
x+y=1 5x-2y=8 3x-y=7 2x-y=3x表示y和用y表示x
X^2-Y^2+6X+10Y-30=0 X^2+Y^2-5X-8Y+21=0 X=?Y=?
2(x-y)=5y,x-y=-5
x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2
x-y / 5y= (y-x)^2 / ( )
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
x*x+2x+y*y-4y+5=0 x= y=
4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
{6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1
6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5