If the four points, whose position vectors are 3 i -4 j +2 k, i +2 j - k,-2 i - j +3 k and 5 i -2 α j +4 k are coplanar, then α is equal to

If the four points, whose position vectors are $\displaystyle 3 \hat{\imath}-4 \hat{\jmath}+2 \hat{k}, \hat{\imath}+2 \hat{\jmath}-\hat{k},-2 \hat{\imath}-\hat{\jmath}+3 \hat{k}$ and $\displaystyle 5 \hat{\imath}-2 \alpha \hat{\jmath}+4 \hat{k}$ are coplanar, then $\displaystyle \alpha$ is equal to