解方程组 1.(x/2+y/5=1 3(x-1)=11+2(y+4)) 2.(5x+4y+z=0 3x+y-4z=11
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解方程组 1.(x/2+y/5=1 3(x-1)=11+2(y+4)) 2.(5x+4y+z=0 3x+y-4z=11 x+y+z=-2 ) 注意看清楚了
详细给过程,直接给答案不给分
详细给过程,直接给答案不给分
![解方程组 1.(x/2+y/5=1 3(x-1)=11+2(y+4)) 2.(5x+4y+z=0 3x+y-4z=11](/uploads/image/z/17888281-25-1.jpg?t=%E8%A7%A3%E6%96%B9%E7%A8%8B%E7%BB%84+1.%EF%BC%88x%2F2%2By%2F5%3D1+3%EF%BC%88x-1%EF%BC%89%3D11%2B2%EF%BC%88y%2B4%EF%BC%89%EF%BC%89+2.%EF%BC%885x%2B4y%2Bz%3D0+3x%2By-4z%3D11)
1.
(1)x/2+y/5=1 (通分)得(3)
(2)3(x-1)=11+2(y+4)(整理得(4)
(3)5x+2y=10
(4)3x-2y=22(与(3)相加)
8x=32
x=4 代入到(3)
2y=10-5x=10-20=-10
y=-5
2、
(1)5x+4y+z=0(与(3)相减得(4)
(2)3x+y-4z=11
(3)x+y+z=-2 (两边×4)得(5)
(4)4x+3y=2(两边×5)得(8)
(5)4x+4y+4z=-8(与(2)相加得(6)
(6)7x+5y=3(两边×3)得(7)
(7)21x+15y=9
(8)20x+15y=10(与(7)相减)
x=-1 代入到(4)
3y=2-4x=2-4(-1)=6
y=2
z=-2-x-y=-2-(-1)-2=-3
验算
(1)5(-1)+4(2)+(-3)=0
(2)-3+2-4(-3)=11
(3)-1+2-3=-2
(1)x/2+y/5=1 (通分)得(3)
(2)3(x-1)=11+2(y+4)(整理得(4)
(3)5x+2y=10
(4)3x-2y=22(与(3)相加)
8x=32
x=4 代入到(3)
2y=10-5x=10-20=-10
y=-5
2、
(1)5x+4y+z=0(与(3)相减得(4)
(2)3x+y-4z=11
(3)x+y+z=-2 (两边×4)得(5)
(4)4x+3y=2(两边×5)得(8)
(5)4x+4y+4z=-8(与(2)相加得(6)
(6)7x+5y=3(两边×3)得(7)
(7)21x+15y=9
(8)20x+15y=10(与(7)相减)
x=-1 代入到(4)
3y=2-4x=2-4(-1)=6
y=2
z=-2-x-y=-2-(-1)-2=-3
验算
(1)5(-1)+4(2)+(-3)=0
(2)-3+2-4(-3)=11
(3)-1+2-3=-2
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