3 and 4 .Determinants and Matrices
hard

જેના માટે $\left|\begin{array}{ccc}1 & \frac{3}{2} & \alpha+\frac{3}{2} \\ 1 & \frac{1}{3} & \alpha+\frac{1}{3} \\ 2 \alpha+3 & 3 \alpha+1 & 0\end{array}\right|=0$ થાય તેવી $\alpha$ ની કિંમત..................... અંતરાલમાં આવે છે.

A

 $(-2,1)$

B

 $(-3,0)$

C

 $\left(-\frac{3}{2}, \frac{3}{2}\right)$

D

 $(0,3)$

(JEE MAIN-2024)

Solution

$\left|\begin{array}{ccc}1 & \frac{3}{2} & \alpha+\frac{3}{2} \\ 1 & \frac{1}{3} & \alpha+\frac{1}{3} \\ 2 \alpha+3 & 3 \alpha+1 & 0\end{array}\right|=0$

$ \Rightarrow(2 \alpha+3)\left\{\frac{7 \alpha}{6}\right\}-(3 \alpha+1)\left\{\frac{-7}{6}\right\}=0 $

$ \Rightarrow(2 \alpha+3) \cdot \frac{7 \alpha}{6}+(3 \alpha+1) \cdot \frac{7}{6}=0 $

$ \Rightarrow 2 \alpha^2+3 \alpha+3 \alpha+1=0 $

$ \Rightarrow 2 \alpha^2+6 \alpha+1=0 $

$ \Rightarrow \alpha=\frac{-3+\sqrt{7}}{2}, \frac{-3-\sqrt{7}}{2}$

Hence option $(2)$ is correct.

Standard 12
Mathematics

Similar Questions

Start a Free Trial Now

Confusing about what to choose? Our team will schedule a demo shortly.