JEE Main 2019MathematicsVector AlgebraEasyMCQ

JEE Main 2019 — Vector Algebra Question with Solution

JEE Main 2019 (08 Apr Shift 2)

Question

Let a→=3i^+2j^+xk^  and b→=i^-j^+k^, for some real x. Then the condition for a→×b→ =r to follow

Choose an option

Show full solutionCorrect option: B
Correct answer
Br≥ 532

Step-by-step explanation

As, We know that a→×b→=i^j^k^32x1-11
=2+xi^+x-3j^-5k^

a→×b→=4+x2+4x+x2+9-6x+25

=2x2-2x+38

Therefore, we have
⇒a→×b→≥752

⇒a→×b→≥532

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About this question

This is a previous-year question from JEE Main 2019, 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.