Let a =3 i + j and b = i +2 j + k. Let c be a vector satisfying a ×( b × c )= b +λ c. If b and c are non-parallel, then the value of λ is:

Let $\displaystyle \overrightarrow{\mathrm{a}}=3 \hat{i}+\hat{j}$ and $\displaystyle \overrightarrow{\mathrm{b}}=\hat{i}+2 \hat{j}+\hat{k}$. Let $\displaystyle \overrightarrow{\mathrm{c}}$ be a vector satisfying $\displaystyle \overrightarrow{\mathrm{a}} \times(\overrightarrow{\mathrm{b}} \times \overrightarrow{\mathrm{c}})=\overrightarrow{\mathrm{b}}+\lambda \overrightarrow{\mathrm{c}}$. If $\displaystyle \overrightarrow{\mathrm{b}}$ and $\displaystyle \overrightarrow{\mathrm{c}}$ are non-parallel, then the value of $\displaystyle \lambda$ is :