七上数学教与学方程组题:x/2-y/3-z/4=3x/2+y/3-z=4x/3-y/2+z/2=3
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![七上数学教与学方程组题:x/2-y/3-z/4=3x/2+y/3-z=4x/3-y/2+z/2=3](/uploads/image/z/14565563-35-3.jpg?t=%E4%B8%83%E4%B8%8A%E6%95%B0%E5%AD%A6%E6%95%99%E4%B8%8E%E5%AD%A6%E6%96%B9%E7%A8%8B%E7%BB%84%E9%A2%98%EF%BC%9Ax%2F2-y%2F3-z%2F4%3D3x%2F2%2By%2F3-z%3D4x%2F3-y%2F2%2Bz%2F2%3D3)
七上数学教与学方程组题:x/2-y/3-z/4=3x/2+y/3-z=4x/3-y/2+z/2=3
七上数学教与学方程组
题:x/2-y/3-z/4=3
x/2+y/3-z=4
x/3-y/2+z/2=3
七上数学教与学方程组题:x/2-y/3-z/4=3x/2+y/3-z=4x/3-y/2+z/2=3
x/2-y/3-z/4=3(1)
x/2+y/3-z=4(2)
x/3-y/2+z/2=3(3)
由(1)*4-(2)得3x/2-5y/3=8,即9x-10y=48(3)
由(3)*2+(2)得7x/6-2y/3=10,即7x-4y=60(4)
由(3)*7-(4)*9得-34y=-204,解得y=6
代入(4)得x=12
代入(2)得z=4
所以方程组解为x=12,y=6,z=4
x/2-y/3-z/4=3 (1)
x/2+y/3-z=4 (2)
x/3-y/2+z/2=3(3)
(1)两边乘以4得 2x-4/3y-z=12 (4)
(3)两边乘以2得 2/3x-y+z=6 (5)
(2)+(5): 7/6x-2/3y=10 (6)
(5)+(3):8/3x-7/3y=18 (7)
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x/2-y/3-z/4=3 (1)
x/2+y/3-z=4 (2)
x/3-y/2+z/2=3(3)
(1)两边乘以4得 2x-4/3y-z=12 (4)
(3)两边乘以2得 2/3x-y+z=6 (5)
(2)+(5): 7/6x-2/3y=10 (6)
(5)+(3):8/3x-7/3y=18 (7)
7*(6)-2*(7): 17/6x=34 x=12 代入(6)得y=6 代入(2)得z=4
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