Question

What vector must be added to the sum of two vectors i-2j-k and 2i+j-k, so that the rest
may be a unit vector along X-axis?
(a) 2i+j-k (b) -2i+j-k (c) 2i-j-k (d) -2i-j-K​

Answer 1

Answer:

-2i+ j+ 2k  to be added to sum of these two vectors. No choices match

Explanation:

Net Vector is  : 1 i + 0 j + 0 k

resolving i   : 1+2 = 3  m so i component must be reduced by 2 , - 2i to be added  ( -2i)

resolving j :  -2 + 1  = -1  , we must add  1 j  to make it zero   ( + j)

resolving k  : -1-1 = -2  , we must add 2j   t make k component zero ( +2k)