JEE Main 2026 · MathsMultiple choiceSingle correctMediumMulti-step

JEE Main 5 April 2026, Shift 1, Maths Q14

Question 14 of 75 in this shift, Maths question 14 of 25, Section A.

Let

\vec{a} = \sqrt{7}\hat{i} + \hat{j} - \hat{k}

and

\vec{b} = \hat{j} + 2\hat{k}

. If

\vec{r}

is a vector such that

\vec{r} \times \vec{a} + \vec{a} \times \vec{b} = \vec{0}

and

\vec{r} \cdot \vec{a} = 0

, then

|3\vec{r}|^2

is equal to:

(1)44Official answer
(2)54
(3)86
(4)132

Official answer

Option 1

NTA final key.

Chapter: Vector Algebra
Topic: Cross Product
Idea tested: Solving Vector Equations with Cross Products

Same idea in other shifts

Asked 8× in all

6 Apr 2026, Shift 1 · Q23If $\vec{a}=\hat{i}+\hat{j}+\hat{k}$ , $\vec{b}=\hat{j}-\hat{k}$ and $\vec{c}$ be three vectors such that $\vec{a}\times\vec{c}=\vec{b}$ …MediumNumerical value
8 Apr 2026, Shift 2 · Q14Let $\vec{a} = 4\hat{i} - \hat{j} + 3\hat{k}$ , $\vec{b} = 10\hat{i} + 2\hat{j} - \hat{k}$ and a vector $\vec{c}$ be such that…MediumSingle correct
9 Apr 2024, Shift 2 · Q17Between the following two statements: Statement I : Let $\vec{a}=\hat{i}+2\hat{j}-3\hat{k}$ and $\vec{b}=2\hat{i}+\hat{j}-\hat{k}$ . Then…HardTwo statements
31 Jan 2024, Shift 1 · Q18Let $\vec{a}=3\hat{i}+\hat{j}-2\hat{k}$ , $\vec{b}=4\hat{i}+\hat{j}+7\hat{k}$ and $\vec{c}=\hat{i}-3\hat{j}+4\hat{k}$ be three vectors. If…MediumSingle correct
31 Jan 2024, Shift 2 · Q30Let $\vec{a}=3\hat{i}+2\hat{j}+\hat{k}$ , $\vec{b}=2\hat{i}-\hat{j}+3\hat{k}$ and $\vec{c}$ be a vector such that…HardNumerical value
24 Jun 2022, Shift 1 · Q16Let $\hat{a}, \hat{b}$ be unit vectors. If $\vec{c}$ be a vector such that the angle between $\hat{a}$ and $\vec{c}$ is $\frac{\pi}{12}$ ,…HardSingle correct
16 Mar 2021, Shift 2 · Q63Let $\vec a=\hat i+2\hat j-3\hat k$ and $\vec b=2\hat i-3\hat j+5\hat k$ . If $\vec r\times\vec a=\vec b\times\vec r$ ,…HardSingle 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 42 of the 174 JEE Main shifts held from 2017 to 2026.