Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Vectors

Question:

Find the value of λ and μ if  (2\(\hat{i}\)+ 6\(\hat{j}\)+ 27 \(\hat{k}\)) × (\(\hat{i}\) +λ\(\hat{j}\) +μ\(\hat{k}\)) =\(\vec{0}\)

Options:

λ = 3 and  μ= 27/2

λ = 2 and  μ= 27/2

λ = 3 and  μ= 29/2

λ = 4 and  μ= 27/2

Correct Answer:

λ = 3 and  μ= 27/2

Explanation:

We have, (2\(\hat{i}\)+ 6\(\hat{j}\)+ 27 \(\hat{k}\)) × (\(\hat{i}\) +λ\(\hat{j}\) +μ\(\hat{k}\)) =\(\vec{0}\)

⇒ (2\(\hat{i}\)+ 6\(\hat{j}\)+ 27 \(\hat{k}\)) × (\(\hat{i}\) +λ\(\hat{j}\) +μ\(\hat{k}\)) =\(\vec{0}\) = (0\(\hat{i}\)+ 0\(\hat{j}\)+ 0 \(\hat{k}\))

⇒ (6μ-27λ)\(\hat{i}\) + (2μ - 27)\(\hat{j}\)+(2λ-6)\(\hat{k}\) = (0\(\hat{i}\)+ 0\(\hat{j}\)+ 0 \(\hat{k}\)) 

on comparing the corresponding components , we have:

(6μ-27λ) = 0,   (2μ - 27) = 0 ,      (2λ-6) =0

solving the above equation, we have    

λ = 3 and  μ= 27/2