For three vectors A =(-x i -6 j -2 k ), B =(- i +4 j +3 k ) and C =(-8 i - j +3 k ), if A ·( B × C )=0, then value of x is ____.

For three vectors $\displaystyle \vec{A}=(-x \hat{i}-6 \hat{j}-2 \hat{k}), \vec{B}=(-\hat{i}+4 \hat{j}+3 \hat{k})$ and $\displaystyle \vec{C}=(-8 \hat{i}-\hat{j}+3 \hat{k})$, if $\displaystyle \vec{A} \cdot(\vec{B} \times \vec{C})=0$, then value of $\displaystyle x$ is $\displaystyle \_\_\_\_$.