Cho các vecto $\stackrel{\to }{i},\stackrel{\to }{j},\stackrel{\to }{k}$ không đồng phẳng. Xét các vecto $\stackrel{\to }{u}=2\stackrel{\to }{i}-\stackrel{\to }{j}+\stackrel{\to }{k}$, $\stackrel{\to }{v}=\stackrel{\to }{i}-2\stackrel{\to }{j}-\stackrel{\to }{k}$, $\stackrel{\to }{w}=x\stackrel{\to }{i}+3\stackrel{\to }{j}+2\stackrel{\to }{k}$ $\left(x\in R\right)$. Tìm x sao cho ba vecto $\stackrel{\to }{u}, \stackrel{\to }{v}, \stackrel{\to }{w}$ đồng phẳng

Cho các vecto $\stackrel{\to }{i}, \stackrel{\to }{j}, \stackrel{\to }{k}$ không đồng phẳng. Xét các vecto $\stackrel{\to }{u}=2\stackrel{\to }{i}-\stackrel{\to }{j}+\stackrel{\to }{k}$ , $\stackrel{\to }{v}=\stackrel{\to }{i}-2\stackrel{\to }{j}-\stackrel{\to }{k}$, $\stackrel{\to }{w}=x\stackrel{\to }{i}+3\stackrel{\to }{j}+2\stackrel{\to }{k}$. Tìm x sao cho ba vecto $\stackrel{\to }{u}, \stackrel{\to }{v}, \stackrel{\to }{w}$ đồng phẳng