Vector Algebra Question 391

Question: The value of $ \lambda $ for which the vectors $ 2\lambda \mathbf{i}+\mathbf{j}-\mathbf{k} $ and $ 2\mathbf{j}+\mathbf{k} $ are perpendicular, is

[MP PET 1992]

Options:

A) None

B) ? 1

C) 1

D) Any value

Show Answer

Answer:

Correct Answer: A

Solution:

  • Since $ (2\lambda \mathbf{i}+\mathbf{j}-\mathbf{k}),.,(2\mathbf{j}+\mathbf{k})=1 $ for every $ \lambda , $ therefore the vectors will not be perpendicular for any $ \lambda . $