Learn

Saturday, 31 October

JEE Main 2021 · MathsNumerical answerNumerical valueEasyCalculation

JEE Main 25 July 2021, Shift 1, Maths Q82

Question 82 of 90 in this shift, Maths question 22 of 30, Section B.

Let p⃗=2i^+3j^+k^\vec{p}=2\hat{i}+3\hat{j}+\hat{k} and q⃗=i^+2j^+k^\vec{q}=\hat{i}+2\hat{j}+\hat{k} be two vectors. If a vector r⃗=(αi^+βj^+γk^)\vec{r}=\left(\alpha\hat{i}+\beta\hat{j}+\gamma\hat{k}\right) is perpendicular to each of the vectors (p⃗+q⃗)\left(\vec{p}+\vec{q}\right) and (p⃗−q⃗)\left(\vec{p}-\vec{q}\right), and ∣r⃗∣=3\left|\vec{r}\right|=\sqrt3, then ∣α∣+∣β∣+∣γ∣|\alpha|+|\beta|+|\gamma| is equal to _________.

Official answer

3

NTA final key.

Same idea in other shifts

Asked 2× in all
  1. 10 Apr 2023, Shift 2 · Q16Let a⃗=2i^+7j^−k^, b⃗=3i^+5k^\vec{a} = 2\hat{i} + 7\hat{j} - \hat{k},\ \vec{b} = 3\hat{i} + 5\hat{k} and c⃗=i^−j^+2k^\vec{c} = \hat{i} - \hat{j} + 2\hat{k}. Let d⃗\vec{d}…MediumSingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.