JEE Main 2018MathematicsVector AlgebraMediumMCQ

JEE Main 2018 — Vector Algebra Question with Solution

JEE Main 2018 (16 Apr Online)

Question

Let a→=i^+j^+k^, c→=j^-k^ and a vector b→ be such that a→×b→=c→ and a→⋅b→=3. Then b→ equals

Choose an option

Show full solutionCorrect option: C
Correct answer
C113

Step-by-step explanation

Given, a→×b→=c→

⇒a→×a→×b→=a→×c→

⇒a→⋅b→a→-a→⋅a→b→=a→×c→

a→×c→=i^j^k^11101-1=-2i^+j^+k^

⇒3a→-3b→=-2i^+j^+k^

⇒3i^+3j^+3k^-3b→=-2 i^+j^+k^

⇒b→=135i^+2j^+2k^

∴ b→=25+4+43

⇒b→=113

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About this question

This is a previous-year question from JEE Main 2018, covering the Vector Algebra chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.