JEE Main 2021 · MathsNumerical answerNumerical valueMediumMulti-step

JEE Main 16 March 2021, Shift 2, Maths Q84

Question 84 of 90 in this shift, Maths question 24 of 30, Section B.

Let

\vec c

be a vector perpendicular to the vectors

\vec a=\hat i+\hat j-\hat k

and

\vec b=\hat i+2\hat j+\hat k

. If

\vec c\cdot(\hat i+\hat j+3\hat k)=8

then the value of

\vec c\cdot(\vec a\times\vec b)

is equal to ________.

Official answer

NTA final key.

Chapter: Vector Algebra
Topic: Triple Products
Idea tested: STP Definition and Determinant

Same topic in other shifts

All Triple Products questions

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
6 Apr 2023, Shift 1 · Q15Let the position vectors of the points A, B, C and D be $5\hat i+5\hat j+2\lambda\hat k$ , $\hat i+2\hat j+3\hat k$ ,…MediumSingle correct
8 Apr 2023, Shift 2 · Q16Let the vectors $\vec{u}_1 = \hat{i} + \hat{j} + a\hat{k}$ , $\vec{u}_2 = \hat{i} + b\hat{j} + \hat{k}$ and…HardSingle correct
25 Jul 2021, Shift 1 · Q71Let the vectors $(2+a+b)\hat{i}+(a+2b+c)\hat{j}-(b+c)\hat{k}$ , $(1+b)\hat{i}+2b\hat{j}-b\hat{k}$ and…MediumSingle correct
8 Jan 2020, Shift 1 · Q66Let the volume of a parallelopiped whose coterminous edges are given by $\vec{u}=\hat{i}+\hat{j}+\lambda\hat{k}$ ,…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 42 of the 174 JEE Main shifts held from 2017 to 2026.