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Saturday, 31 October

JEE Main 2021 · MathsMultiple choiceSingle correctEasyApplication

JEE Main 4 August 2021, Shift 1, Maths Q76

Question 76 of 90 in this shift, Maths question 16 of 30, Section A.

If a⃗=i^+j^+k^\vec{a}=\hat{i}+\hat{j}+\hat{k}, b⃗=4i^−2j^+3k^\vec{b}=4\hat{i}-2\hat{j}+3\hat{k} and c⃗=i^−2j^+k^\vec{c}=\hat{i}-2\hat{j}+\hat{k} are three vectors, then a vector of magnitude 6 units, which is parallel to the vector 2a⃗−b⃗+3c⃗2\vec{a}-\vec{b}+3\vec{c}, is
  1. (1)2i^+4j^+4k^2\hat{i}+4\hat{j}+4\hat{k}
  2. (2)4i^+2j^−4k^4\hat{i}+2\hat{j}-4\hat{k}
  3. (3)2i^−4j^+4k^2\hat{i}-4\hat{j}+4\hat{k}Official answer
  4. (4)4i^+4j^−2k^4\hat{i}+4\hat{j}-2\hat{k}

Official answer

Option 3

NTA final key.

Topic
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Idea tested
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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 108 of the 174 JEE Main shifts held from 2017 to 2026.