The vectors i + 2j + 3k, i + 4j + 7k, - 3i - 2j - 5k are collinea… - Vidyadip

MCQ

The vectors $i + 2j + 3k,$ $\lambda i + 4j + 7k,$ $ - 3i - 2j - 5k$ are collinear, if $\lambda$ equals

✓
$3$
B
$4$
C
$5$
D
$6$

✓

Answer

Correct option: A.

$3$

a
(a) $\left| {\begin{array}{*{20}{c}}1&2&3\\\lambda &4&7\\{ - 3}&{ - 2}&{ - 5}\end{array}} \right|\, = 0 \Rightarrow \lambda = 3.$

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