If two vectors P = i + 2mj + mk and Q = 4i - 2j + mk are perpendicular to each other. Then, the value of m will be: (a) -1 (b) 3 (c) 1 (d) 2

Answer: (d). P · Q = 4 - 4m + m² = 0 (m - 2)² = 0 ⇒ m = 2, answer (d).

If two vectors P = i + 2mj + mk and Q = 4i - 2j + mk are… | JEE Main 2023 (24 Jan, Shift 2)

Q16JEE Main 2023 · 24 JAN · SHIFT 2Easy

Scalar (Dot) Product

If two vectors $\vec{P} = \hat{i} + 2m\hat{j} + m\hat{k}$ and $\vec{Q} = 4\hat{i} - 2\hat{j} + m\hat{k}$ are perpendicular to each other. Then, the value of m will be:

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Answer: (d)

$\vec{P} \cdot \vec{Q} = 4 - 4m + m^2 = 0$
$(m - 2)^2 = 0 \Rightarrow m = 2$ , answer (d).

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Scalar (Dot) Product question from JEE Main 2023 (24 Jan, Shift 2)

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