The vector 2 ,i + a ,j + k is perpendicular to the vector 2 ,i - … - Vidyadip

MCQ

The vector $2\,i + a\,j + k$ is perpendicular to the vector $2\,i - j - k,$ if $a = $

A
$5$
B
$-5$
C
$-3$
✓
$3$

✓

Answer

Correct option: D.

$3$

d
(d) $a.b = 0 = 4 - a - 1 \Rightarrow a = 3.$

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