JEE Main 2025 — Determinants Question with Solution
JEE Main 2025 (24 Jan Shift 2)
Question
For some , let . Then is equal to :
Choose an option
Show full solutionCorrect option: A
Correct answer
A16
Step-by-step explanation
$\lim _{x \rightarrow 0}\left|\begin{array}{ccc}
a+\frac{\sin x}{x} & 1 & b \\
a & 1+\frac{\sin x}{x} & b \\
a & 1 & b+\frac{\sin x}{x}
\end{array}\right|=\lambda+\mu a+v b$
At ,
$\begin{aligned}
& f(x)=\left|\begin{array}{ccc}
a+1 & 1 & b \\
a & 1+1 & b \\
a & 1 & b+1
\end{array}\right|=\lambda+\mu a+v b \\
& R_1 \rightarrow R_1-R_2 \\
& R_2 \rightarrow R_2-R_3 \\
& \left|\begin{array}{ccc}
1 & -1 & 0 \\
0 & 1 & -1 \\
a & 1 & b+1
\end{array}\right|=\lambda+\mu a+v b \\
& \mathrm{C}_2 \rightarrow \mathrm{C}_1-\mathrm{C}_2 \\
& \left|\begin{array}{ccc}
1 & 0 & 0 \\
0 & 1 & -1 \\
a & a+1 & b+1
\end{array}\right|=\lambda+\mu a+v b \\
& a+b+2=\lambda+\mu a+v b \\
& \lambda=2, \mu=1, \quad v=1 \\
& (\lambda+\mu+v)=(2+1+1)^2=16
\end{aligned}$
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This is a previous-year question from JEE Main 2025, covering the Determinants chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.