JEE Main 2024 · MathsMultiple choiceSingle correctMediumCalculation

JEE Main 1 February 2024, Shift 1, Maths Q19

Question 19 of 90 in this shift, Maths question 19 of 30, Section A.

Let

\vec{a}=-5\hat{i}+\hat{j}-3\hat{k}

\vec{b}=\hat{i}+2\hat{j}-4\hat{k}

and

\vec{c}=\left(\left(\left(\vec{a}\times\vec{b}\right)\times\hat{i}\right)\times\hat{i}\right)\times\hat{i}

. Then

\vec{c}\cdot\left(-\hat{i}+\hat{j}+\hat{k}\right)

is equal to :

(1) $-10$
(2) $-12$ Official answer
(3) $-13$
(4) $-15$

Official answer

Option 2

NTA final key.

Chapter: Vector Algebra
Topic: Triple Products
Idea tested: VTP with Repeated Vectors

Same idea in other shifts

Asked 3× in all

6 Apr 2024, Shift 2 · Q18Let $\vec{a}=2\hat{i}+\hat{j}-\hat{k}$ , $\vec{b}=\left(\left(\vec{a}\times(\hat{i}+\hat{j})\right)\times\hat{i}\right)\times\hat{i}$ . Then…MediumSingle correct
26 Feb 2021, Shift 1 · Q61If $\vec{a}$ and $\vec{b}$ are perpendicular, then $\vec{a}\times(\vec{a}\times(\vec{a}\times(\vec{a}\times\vec{b})))$ is equal to :EasySingle 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.