(1)x:y:z=3:2:5,2x+3y+8=5 (2)5x-3y+z=5,4x+3y-2z=9x-5y-z=-17
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(1)x:y:z=3:2:5,2x+3y+8=5(2)5x-3y+z=5,4x+3y-2z=9x-5y-z=-17(1)x:y:z=3:2:5,2x+3y+8=5(2)5x-3y+z=5,4x+3y-
(1)x:y:z=3:2:5,2x+3y+8=5 (2)5x-3y+z=5,4x+3y-2z=9x-5y-z=-17
(1)x:y:z=3:2:5,2x+3y+8=5 (2)5x-3y+z=5,4x+3y-2z=9x-5y-z=-17
(1)x:y:z=3:2:5,2x+3y+8=5 (2)5x-3y+z=5,4x+3y-2z=9x-5y-z=-17
(1) 设x=3t,则y=2t,z=5t
代入2x+3y+8=5 是不是少一个z
得6t+6t+8=5
∴t=-1/4
∴x=-3/4
y=-1/2
z=-5/4
(2)
(1)×2+(2)得
14x-3y=19 (4)
(1)+(3)得
6x-8y=-12 (5)
解(4)(5)组成的方程组得
x=2
y=3
把x=2,y=3代入(1)得
10-9+z=5
∴z=4
∴方程组的解为
x=2,y=3,z=4
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x/2=y/3=z/5 x+3y-z/x-3y+z
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{x+y+z=1 x-2y+3z=5 2x-3y-3z=-8
2x-y+3z=3 {3X+Y-2Z=-1 X+Y+Z=5
x+y+z=-5,3x+y+z=1,4x+3y+2z=-2快
3x+2y+z=14 ,x+y+z=10,z+2x+3y=1 5