If vectors 2î − ĵ + k̂, î + 2ĵ − 3k̂ and 3î + λĵ + 5k̂ are coplanar, then the value of λ is:
If vectors 2î − ĵ + k̂, î + 2ĵ − 3k̂ and 3î + λĵ + 5k̂ are coplanar, then the value of λ is:
- A. 4
- B. −4
- C. 2
- D. −2
Answer: B) −4
Explanation: For coplanar vectors, their scalar triple product is zero. Det: 2(10 + 3λ) − (−1)(5 + 9) + 1(λ − 6) = 0. 20 + 6λ + 14 + λ − 6 = 0. 7λ + 28 = 0. λ = −4.
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