Q. The value of $\left\lbrack 2\ \widehat{\mathbf{i}}\ 3\widehat{\mathbf{j}} - 5\widehat{\mathbf{k}}\ \right\rbrack$ is equal to
A) $- 30$
B) $- 25$
C) 0
D) 11
Explanation
(a)
$\left\lbrack 2\mathbf{\ }\widehat{\mathbf{i}}\ 3\widehat{\mathbf{j}} - 5\widehat{\mathbf{k}}\ \right\rbrack$
$= - 30\ \left\lbrack \mathbf{\ }\widehat{\mathbf{i}}\mathbf{\ \ }\widehat{\mathbf{j}}\mathbf{\ }\widehat{\mathbf{k}}\ \right\rbrack$
$= - 30\ \ \ \ \left( \because\left\lbrack \ \widehat{\mathbf{i}}\mathbf{\ \ }\widehat{\mathbf{j}}\mathbf{\ }\widehat{\mathbf{k}}\ \right\rbrack = 1\ \right)$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.