Let a → = i ^ + j ^ + k ^ , b → = 2 i ^ - 3 j ^ + 4 k ^ and a → × c → = b → + 2 λ a → , then the value of a → b → c → is equal to

Question

Let a → = i ^ + j ^ + k ^ , b → = 2 i ^ - 3 j ^ + 4 k ^ and a → × c → = b → + 2 λ a → , then the value of a → b → c → is equal to, 12, 26, - 26, 3

MARKS App · Accepted Answer

a → × c → = b → + 2 λ a → Taking dot product with a → 0 = b → ⋅ a → + 2 λ a → ⋅ a → ⇒ 0 = 3 + 6 λ ⇒ λ = - 1 2 i.e. a → × c → = b → - a → Taking dot product with b → a → × c → ⋅ b → = b → ⋅ b → - a → ⋅ b → ⇒ a → c → b → = 29 - 3 ⇒ a → b → c → = - 26

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