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Question: Answered & Verified by Expert
If  a, b and c are three vectors, such that a=2, b=3, c=4, ac=0, ab=0 and the angle between b and c is π3, then the value of a×2b-3c is equal to
MathematicsVector AlgebraJEE Main
Options:
  • A 123
  • B 63
  • C 33
  • D 5
Solution:
2647 Upvotes Verified Answer
The correct answer is: 123
2b-3c2=4b2+9c2-12bc
=36+144-12×3×4×12
=108
2b-3c=63
As we know that,
a×2b-3c2+a2b-3c2=a22b-3c2
a×2b-3c2+0=4×108
a×2b-3c=123

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