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99 Percentile Qs Bank for JEE MainMathematicsVector Algebra

If a → = 3 , | b → | = 4 , then a value of λ for which a → + λ b → is perpendicular to a → - λ b → , is

Options

  1. A9 16
  2. B3 4
  3. C3 2
  4. D4 3

Correct answer

B. 3 4

Step-by-step solution

Given that, a → = 3 , | b → | = 4 and a → + λ b → is perpendicular to a → - λ b → . ∴ a → + λ b → ⋅ a → - λ b → = 0 ⇒ a → ⋅ a → - a → ⋅ b → λ + λ b → ⋅ a → - λ 2 b → ⋅ b → = 0 ⇒ a → 2 - λ 2 b → 2 = 0 ⇒ λ 2 = a → 2 b → 2 ⇒ λ = a → b → = 3 4

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