If a → = i ^ + j ^ + k ^ , b → = 2 i ^ + λ + k ^ , c → = i ^ − j ^ + 4 k ^ and a → . ( b → × c → ) = 10 , then λ is equal to

Question

If a → = i ^ + j ^ + k ^ , b → = 2 i ^ + λ + k ^ , c → = i ^ − j ^ + 4 k ^ and a → . ( b → × c → ) = 10 , then λ is equal to, 6, 7, 9, 10

MARKS App · Accepted Answer

1 1 1 2 λ 1 1 - 1 4 = 10 1 4 λ + 1 - 1 8 - 1 + 1 - 2 - λ = 10 ⇒ 4 λ + 1 - 7 - 2 - λ = 10 ⇒ 3 λ = 18 ⇒ λ = 6