已知,x,y,z同时满足2x+3y=8,9y+2z=0,x-z=-2,求xyz的值
已知,x,y,z同时满足2x+3y=8,9y+2z=0,x-z=-2,求xyz的值
数学人气:998 ℃时间:2020-02-03 08:07:54
优质解答
2x+3y=8 (1) 9y+2z=0 (2) x-z=-2 (3) (2)+(3)×2 2x+9y=-4 (4) (4)-(1) 6y=-12 y=-2 x=(8-3y)/2=7 z=x+2=9所以 x=7,y=-2,z=9 所以xyz=-126
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