Question

The vector which must be added to the sum of the two vectors $\widehat{i} + 2\widehat{j} - \widehat{k}$ and $\widehat{i} - 2\widehat{j} + 2\widehat{k}$ to get a resultant of unit vector along z-axis is –

• A. (a)$2\widehat{i} + \widehat{j}$
• A. (b)$- 2\widehat{i}$
• A. (c)$\widehat{i} + \widehat{j} + \widehat{k}$
• A. (d)$\widehat{i} - \widehat{j} - \widehat{k}$

Answer 1

(b)

$\overrightarrow{A}$+($\widehat{i} + 2\widehat{j} - \widehat{k}$) + $\widehat{i}–2\widehat{j} + 2\widehat{k}$= $\widehat{k}$

$\overrightarrow{A}$ = – 2$\widehat{i}$