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MHT CET · Maths · Vector Algebra

\(\bar{a}=\hat{i}+\hat{j}+\hat{k}, \bar{b}=4 \hat{i}-2 \hat{j}+3 \hat{k}, \bar{c}=\hat{i}-2 \hat{j}+\hat{k}\), then \(a\) vector of magnitude 6 units, which is parallel to the vector \(2 \bar{a}-\bar{b}+3 c\), is

  1. A \(2 \hat{i}-4 \hat{j}+4 \hat{k}\)
  2. B \(\hat{i}-\hat{j}+2 \hat{k}\)
  3. C \(4 \hat{i}+4 \hat{j}-2 \hat{k}\)
  4. D \(2 \hat{\mathrm{i}}+4 \hat{\mathrm{j}}+4 \hat{\mathrm{k}}\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(2 \hat{i}-4 \hat{j}+4 \hat{k}\)

Step-by-step Solution

Detailed explanation

\(\begin{aligned}
& \overline{\mathrm{a}}-\overline{\mathrm{b}}+3 \overline{\mathrm{c}} \\
= & (2-4+3) \hat{\mathrm{i}}+(2+2-6) \hat{\mathrm{j}}+(2-3+3) \hat{\mathrm{k}} \\
= & \hat{\mathrm{i}}-2 \hat{\mathrm{j}}+2 \hat{\mathrm{k}}
\end{aligned}\)
\(\therefore \quad\) Required vector is the multiple of the above vector and has magnitude 6 units.
Option (A) satisfies this condition.