JEE Mains · Maths · STD 12 - 3 and 4 . metrices and determinant
If the system of linear equations :
\(\begin{aligned}
& x+y+2 z=6 \\
& 2 x+3 y+\mathrm{a} z=\mathrm{a}+1 \\
& -x-3 y+\mathrm{b} z=2 \mathrm{~b}
\end{aligned}\)
where \(a, b \in \mathbf{R}\), has infinitely many solutions, then \(7 a+3 b\) is equal to :
- A 16
- B 12
- C 22
- D 9
Answer & Solution
Correct Answer
(A) 16
Step-by-step Solution
Detailed explanation
The given equations are \(\begin{aligned} & x+y+2 z=6 \\ & 2 x+3 y+a z=a+1 \\ & -x-3 y+b z=2 b, \text { where } a, b, \in \mathbf{R} \end{aligned}\) For infinite many solutions: \(D=D_1=D_2=D_3=0\)…
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