Q. If position vector of point $A$ is $\overrightarrow{\mathbf{a}} + 2\overrightarrow{\mathbf{b}}$ and any point $P(\overrightarrow{\mathbf{a})}$ divides $\overrightarrow{\mathbf{AB}}$ in the ratio of $2\ :3$, then position vector of $B$ is

A) $2\ \overrightarrow{\mathbf{a}}\mathbf{-}\overrightarrow{\mathbf{b}}$
B) $\overrightarrow{\mathbf{b}} - 2\overrightarrow{\mathbf{a}}$
C) $\overrightarrow{\mathbf{a}} - 3\overrightarrow{\mathbf{b}}$
D) $\overrightarrow{\mathbf{b}}$
Explanation

(c)
Let the position of $B$ is $\overrightarrow{\mathbf{r}}$.
$\therefore\ \overrightarrow{\mathbf{a}} = \frac{2\overrightarrow{\mathbf{r}} + 3(\overrightarrow{\mathbf{a}} + 2\overrightarrow{\mathbf{b}})}{2 + 3}$
[image:10_image6.emf]
$\Rightarrow 5\overrightarrow{\mathbf{a}} = 2\overrightarrow{\mathbf{r}} + 3\overrightarrow{\mathbf{a}} + 6\overrightarrow{\mathbf{b}}$
$\Rightarrow \ 2\overrightarrow{\mathbf{r}} = 2\overrightarrow{\mathbf{a}} - 6\overrightarrow{\mathbf{b}}$
$\therefore\ \overrightarrow{\mathbf{r}} = \overrightarrow{\mathbf{a}} - 3\overrightarrow{\mathbf{b}}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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