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JEE Main202331 Jan 2023Morning ShiftMathematicsVector AlgebraActual

Let a → = 2 i ^ + j ^ + k ^ , and b → and c → be two nonzero vectors such that a → + b → + c → = a → + b → - c → and b → · c → = 0 . Consider the following two statement: A a → + λ c → ≥ a → for all λ ∈ ℝ . B a → and c → are always parallel

Options

  1. Aonly (B) is correct
  2. Bneither (A) nor (B) is correct
  3. Conly (A) is correct
  4. Dboth (A) and (B) are correct.

Correct answer

C. only (A) is correct

Step-by-step solution

Given, a → + b → + c → = a → + b → - c → Now squaring both side we get, ⇒ a → + b → + c → 2 = a → + b → - c → 2 ⇒ a → 2 + b → 2 + c → 2 + 2 a → · b → + 2 b → · c → + 2 c → · a → = a → 2 + b → 2 + c → 2 + 2 a → · b → - 2 b → · c → - 2 c → · a → ⇒ 2 b → · c → + 2 c → &#1

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