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MHT CET2019Morning ShiftMathematicsVector AlgebraActual

If the scalar triple product of the vectors - 3 i ^ + 7 j ^ - 3 k ^ , 3 i ^ - 7 j ^ + λ k ^ and 7 i ^ - 5 j ^ - 3 k ^ is 272 then λ = …

Options

  1. A9
  2. B11
  3. C8
  4. D10

Correct answer

B. 11

Step-by-step solution

Scalar triple product of the given vectors is 272. ∴ - 3 7 - 3 3 - 7 λ 7 - 5 - 3 = 272 ( ∵ scalar triple product of the vectors a, b and c is [a b c]) ⇒ - 3 21 + 5 λ - 7 - 9 - 7 λ - 3 - 15 + 49 = 272 ⇒ - 63 - 15 λ + 63 + 49 λ - 102 = 272 ⇒ 34 λ - 102 = 272 ⇒ 34 λ = 37 4 ⇒ λ = 1 1

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