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JEE Mains · Maths · STD 12 - 10. vector algebra

Let \(\vec{v}=\alpha \hat{i}+2 \hat{j}-3 \hat{k}, \vec{w}=2 \alpha \hat{i}+\hat{j}-\hat{k}\), and \(\overrightarrow{ u }\) be a vector such that \(|\vec{u}|=\alpha > 0\). If the minimum value of the scalar triple product \([\vec{u} \vec{v} \vec{w}]\) is \(-\alpha \sqrt{3401}\), and \(|\vec{u} . \hat{i}|^2=\frac{m}{n}\) where \(m\) and \(n\) are coprime natural numbers, then \(m + n\) is equal to \(.........\).

  1. A \(3502\)
  2. B \(3503\)
  3. C \(3501\)
  4. D \(3504\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(3501\)

Step-by-step Solution

Detailed explanation

\({[\vec{u} \vec{v} \vec{w}]=\vec{u} \cdot(\vec{v} \times \vec{w})}\) \(\min .(|u||\vec{v} \times \vec{w}| \cos \theta)=-\alpha \sqrt{3401}\) \(\cos \theta=-1\) \(|u|=\alpha \text { (Given) }\) \(|\vec{v} \times \vec{w}|=\sqrt{3401}\)…