3Q一定要有过程.1】 x-2y= ─9 2】3x-y+z=4 3】y=2x-7 4】4x+9x=12 y-z=3 2x+3y-z=12 5x+3y+2z=2 3y-2z=1 2z+x=47 x+y+z=6 3x-4z=4 7x+5z=4/19 4】x:y=3:2 5】x+y+z=26 6】x+y=3 7】x-y-z=2 y:z=5:4 x-y=1 y+z=5 y-z-x= ─5 x+y+z=66 2x-y+z=18
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![3Q一定要有过程.1】 x-2y= ─9 2】3x-y+z=4 3】y=2x-7 4】4x+9x=12 y-z=3 2x+3y-z=12 5x+3y+2z=2 3y-2z=1 2z+x=47 x+y+z=6 3x-4z=4 7x+5z=4/19 4】x:y=3:2 5】x+y+z=26 6】x+y=3 7】x-y-z=2 y:z=5:4 x-y=1 y+z=5 y-z-x= ─5 x+y+z=66 2x-y+z=18](/uploads/image/z/3019106-2-6.jpg?t=3Q%E4%B8%80%E5%AE%9A%E8%A6%81%E6%9C%89%E8%BF%87%E7%A8%8B.1%E3%80%91+x-2y%3D+%E2%94%809+2%E3%80%913x-y%2Bz%3D4+3%E3%80%91y%3D2x-7+4%E3%80%914x%2B9x%3D12+y-z%3D3+2x%2B3y-z%3D12+5x%2B3y%2B2z%3D2+3y-2z%3D1+2z%2Bx%3D47+x%2By%2Bz%3D6+3x-4z%3D4+7x%2B5z%3D4%2F19+4%E3%80%91x%EF%BC%9Ay%3D3%EF%BC%9A2+5%E3%80%91x%2By%2Bz%3D26+6%E3%80%91x%2By%3D3+7%E3%80%91x-y-z%3D2+y%EF%BC%9Az%3D5%EF%BC%9A4+x-y%3D1+y%2Bz%3D5+y-z-x%3D+%E2%94%805+x%2By%2Bz%3D66+2x-y%2Bz%3D18)
3Q一定要有过程.1】 x-2y= ─9 2】3x-y+z=4 3】y=2x-7 4】4x+9x=12 y-z=3 2x+3y-z=12 5x+3y+2z=2 3y-2z=1 2z+x=47 x+y+z=6 3x-4z=4 7x+5z=4/19 4】x:y=3:2 5】x+y+z=26 6】x+y=3 7】x-y-z=2 y:z=5:4 x-y=1 y+z=5 y-z-x= ─5 x+y+z=66 2x-y+z=18
3Q
一定要有过程.1】 x-2y= ─9 2】3x-y+z=4 3】y=2x-7 4】4x+9x=12 y-z=3 2x+3y-z=12 5x+3y+2z=2 3y-2z=1 2z+x=47 x+y+z=6 3x-4z=4 7x+5z=4/19 4】x:y=3:2 5】x+y+z=26 6】x+y=3 7】x-y-z=2 y:z=5:4 x-y=1 y+z=5 y-z-x= ─5 x+y+z=66 2x-y+z=18 z+x=6 z-x-y=4
3Q一定要有过程.1】 x-2y= ─9 2】3x-y+z=4 3】y=2x-7 4】4x+9x=12 y-z=3 2x+3y-z=12 5x+3y+2z=2 3y-2z=1 2z+x=47 x+y+z=6 3x-4z=4 7x+5z=4/19 4】x:y=3:2 5】x+y+z=26 6】x+y=3 7】x-y-z=2 y:z=5:4 x-y=1 y+z=5 y-z-x= ─5 x+y+z=66 2x-y+z=18
代入消元法 (1)X=2Y-92代入2Z+X=47得2Y+2Z=139 即Y+Z=69.5 再联立Y-Z=3解之得 Y=36.25 Z=33.25 X=-19.5 其余题目同上述方法解就行了