解下列方程组:(1){2x+y=-2,2x-y=6(2)0.25x-0.5y=2,0.4x+0.25y=20(3)2x+3y=-1,2分之x+3分之x=1
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![解下列方程组:(1){2x+y=-2,2x-y=6(2)0.25x-0.5y=2,0.4x+0.25y=20(3)2x+3y=-1,2分之x+3分之x=1](/uploads/image/z/5528330-26-0.jpg?t=%E8%A7%A3%E4%B8%8B%E5%88%97%E6%96%B9%E7%A8%8B%E7%BB%84%3A%281%29%7B2x%2By%3D-2%2C2x-y%3D6%EF%BC%882%EF%BC%890.25x-0.5y%3D2%2C0.4x%2B0.25y%3D20%EF%BC%883%EF%BC%892x%2B3y%3D-1%2C2%E5%88%86%E4%B9%8Bx%2B3%E5%88%86%E4%B9%8Bx%3D1)
解下列方程组:(1){2x+y=-2,2x-y=6(2)0.25x-0.5y=2,0.4x+0.25y=20(3)2x+3y=-1,2分之x+3分之x=1
解下列方程组:(1){2x+y=-2,2x-y=6
(2)0.25x-0.5y=2,0.4x+0.25y=20(3)2x+3y=-1,2分之x+3分之x=1
解下列方程组:(1){2x+y=-2,2x-y=6(2)0.25x-0.5y=2,0.4x+0.25y=20(3)2x+3y=-1,2分之x+3分之x=1
1、两式相加得4X=4,X=1;Y=-4
2、0.4x+0.25y=20两边乘以2得0.8X+0.5Y=40
两式相加得1.05X=42,X=4;Y=-2
3、X/2+Y/3=1两边同乘以6得3X+2Y=6,X=(6-2Y)/3代入2x+3y=-1得
Y=-3;X=4
(1) 2x+y=-2 ①
2x-y=6 ②
①+②,得 4x=4
即x=1
将x=1代入①,得y=-4
(2) 0.25x-0.5y=2 ①
0.4x+0.25y=20 ②
①+②*2,得 1.05x=42
即x=4...
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(1) 2x+y=-2 ①
2x-y=6 ②
①+②,得 4x=4
即x=1
将x=1代入①,得y=-4
(2) 0.25x-0.5y=2 ①
0.4x+0.25y=20 ②
①+②*2,得 1.05x=42
即x=40
将x=40代入①,得y=16
3)2x+3y=-1 ①
x/2+y/3=1 ②
①-②*4,得 5y/3=-5
即y=-3
将y=-3代入①,得x=4
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