# If $\overrightarrow a=\hat i+\hat j+\hat k,\:\overrightarrow b=\hat i\:\:and\:\:\overrightarrow c=x\hat i-\hat j+\hat k$, then the value of $x$ for which $\overrightarrow a\:\overrightarrow b\:and\:\overrightarrow c$ are coplanar is ?
$\begin{array}{1 1} 0 \\ - 1 \\ 1 \\ \text{cannot be coplanar for any x } \end{array}$