Let a→=2i^-j^+3k^, b→=i^+j^-4k^ and non-zero vector c→ are such that a→×b→×c→=a→×b→×c→, then vector c→ may be

Correct answer: (A) 4i^-2j^+6k^. a→×b→×c→=a→×b→×c→ a → ⋅ c → b → − b → ⋅ c → a → = a → ⋅ c → b → − a → ⋅ b → c → ⇒c→ must be parallel to a→

Q7 / 100 · NTA Abhyas (JEE Main) 2020 · Mathematics · Vector Algebra

Let $\vec{a} = 2 \hat{i} - \hat{j} + 3 \hat{k}$ , $\vec{b} = \hat{i} + \hat{j} - 4 \hat{k}$ and non-zero vector $\vec{c}$ are such that $(\vec{a} \times \vec{b}) \times \vec{c} = \vec{a} \times (\vec{b} \times \vec{c})$ , then vector $\vec{c}$ may be

(\vec{a} \times \vec{b}) \times \vec{c} = \vec{a} \times (\vec{b} \times \vec{c})

(\vec{a} \cdot \vec{c}) \vec{b} - (\vec{b} \cdot \vec{c}) \vec{a} = (\vec{a} \cdot \vec{c}) \vec{b} - (\vec{a} \cdot \vec{b}) \vec{c}

\Rightarrow \vec{c}

must be parallel to

\vec{a}

Hence, the correct answer is option: 'A'.