3 and 4 .Determinants and Matrices
medium

જો સમીકરણ સંહતિ

$x+y+a z=b$

$2 x+5 y+2 z=6$

$x+2 y+3 z=3$

ને અસંખ્ય ઉકેલો હોય, તો $2 a+3 b=.......$

A

$23$

B

$28$

C

$25$

D

$20$

(JEE MAIN-2023)

Solution

$\Delta=\left|\begin{array}{lll}1 & 1 & a \\ 2 & 5 & 2 \\ 1 & 2 & 3\end{array}\right|=0 \Rightarrow 11-4- a =0$

$a=7$

$\Delta_1=\left|\begin{array}{lll} b & 1 & a \\ 6 & 5 & 2 \\ 3 & 2 & 3\end{array}\right|=0 \Rightarrow 11 b -12-21=0$

$b =3$

$2 a+3 b=23$

Standard 12
Mathematics

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