3 and 4 .Determinants and Matrices
medium

If the system of equations  $k x+y+2 z=1$ ; $3 x-y-2 z=2$ ; $-2 x-2 y-4 z=3$ has infinitely many solutions, then $k$ is equal to ..........

A

$21$

B

$42$

C

$14$

D

$28$

(JEE MAIN-2021)

Solution

We observe $5 P _{2}- P _{1}=3 P _{3}$

So, $15- K =-6$

$\Rightarrow K =21$

Standard 12
Mathematics

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