If the vectors $\hat{i}+2 \hat{\jmath}+x \hat{k}$ and $y t+6 \hat{k}+4 \hat{k}$ are collinear, then the…

If the vectors $\hat{i}+2 \hat{\jmath}+x \hat{k}$ and $y t+6 \hat{k}+4 \hat{k}$ are collinear, then the values of $x$ and $y$ are respectively,
  1. $\frac{4}{3}, 3$
  2. 3,4
  3. $\frac{1}{3}, 1$
  4. 4,3

Solution

Let $\bar{a} \& \bar{b}$ be given collinear vectors $\begin{array}{l} \therefore \overline{\mathrm{a}}=\mathrm{m} \overline{\mathrm{b}} \\ \therefore \quad \hat{\mathrm{i}}+2 \hat{\mathrm{j}}+\mathrm{x} \hat{\mathrm{k}}=\mathrm{m}(\mathrm{yi}+6 \hat{\mathrm{j}}+4 \hat{\mathrm{k}}) \\ \therefore \quad \hat{\mathrm{i}}+2 \hat{\mathrm{j}}+\mathrm{xk}=\mathrm{my} \hat{\mathrm{i}}+6 \mathrm{~m} \hat{\mathrm{j}}+4 \mathrm{mk} \\ \therefore \quad 1=\mathrm{my}, 2=6 \mathrm{~m}, \mathrm{x}=4 \mathrm{~m} \Rightarrow \mathrm{m}=\frac{1}{3}, \mathrm{y}=3, \mathrm{x}=\frac{4}{3} \end{array}$

Asked in: MHT CET 2020 (13 Oct Shift 2)

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