JEE Main 2021 · MathsMultiple choiceSingle correctMediumMulti-step

JEE Main 25 July 2021, Shift 1, Maths Q71

Question 71 of 90 in this shift, Maths question 11 of 30, Section A.

Let 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

(2+b)\hat{i}+2b\hat{j}+(1-b)\hat{k}

a,b,c\in\mathbf{R}

be co-planar. Then which of the following is true ?

(1) $2b=a+c$ Official answer
(2) $2a=b+c$
(3) $3c=a+b$
(4) $a=b+2c$

Official answer

Option 1

NTA final key.

Chapter: Vector Algebra
Topic: Triple Products
Idea tested: Solving for Unknown in Coplanarity

Same topic in other shifts

All Triple Products questions

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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.