共50条信息
已知向量\( \overset{→}{AB} =(1,5,-2)\),\( \overset{→}{BC} =(3,1,2)\),\( \overset{→}{DE} =(x,-3,6).\)若\(DE/\!/\)平面\(ABC\),则\(x\)的值是\((\) \()\)
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