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Question: Answered & Verified by Expert
If a+lb+l2c=0 and a×b+b×c+c×a=3b×c, then the minimum value of such l is
MathematicsVector AlgebraTS EAMCETTS EAMCET 2020 (09 Sep Shift 1)
Options:
  • A 1
  • B -2
  • C -94
  • D 0
Solution:
2164 Upvotes Verified Answer
The correct answer is: -2

Given: a×b+c×a=2b×c

a×b-c=2b×c  ...i

Also a+lb+l2c=0

multiply both sides by b-c

a×b-c+lb×b-c+l2c×b-c=0

a×b-c+l-b×c+l2c×b=0

a×b-c=l+l2b×c  ...ii

From i & ii l+l2=2

So minimum value of l that satisfied the equation is l=-2

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