JEE Main 2026 (Online) 4th April Evening ShiftQuestion 1
If the system of equations:
$x+y+z=5$
$x+2y+3z=9$
$x+3y+\lambda z=\mu$
has infinitely many solutions, then the value of $\lambda+\mu$ is:
Determinant
Solution
$\Delta=\lambda-5=0\Rightarrow\lambda=5$. Consistency: $\begin{vmatrix}1&1&5\\1&2&9\\1&3&\mu\end{vmatrix}=0\Rightarrow \mu=13$. $\lambda+\mu=18$. Option (B).