What vector must be added to the two vectors `hati-2hatj+2hatk` and `2hati+hatj-hatk`, so that the resultant may be a unit vector along `x`- axis

Options

A. `5hati +hatk`
B. `-5hati +3hatj`
C. `3hati +5hatk`
D. `-3hati +2hatk`

Answer

B

Explanation

(b) `A=2hati-hatj+3hatk and B=3hati-2hatj-2hatk`
resultant `R=hatk =A+B+C `
`hatk =(2hati-hatj+3hatk)+(3hati-2hatj-2hatk)+C`
`hatk=5hati-3hatj+hatk+C`
`C=-5hati+3hatj`