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​Solve the Following Determinant Equation: ∣ ∣ ∣ ∣ X + 1 3 5 2 X + 2 5 2 3 X + 4 ∣ ∣ ∣ ∣ = 0 - Mathematics

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Question

​Solve the following determinant equation:

\[\begin{vmatrix}x + 1 & 3 & 5 \\ 2 & x + 2 & 5 \\ 2 & 3 & x + 4\end{vmatrix} = 0\]

 

Solution

\[\text{ Let }∆ = \begin{vmatrix}x + 1 & 3 & 5 \\ 2 & x + 2 & 5 \\ 2 & 3 & x + 4\end{vmatrix}\] 

\[ = \begin{vmatrix}x + 9 & 3 & 5 \\ x + 9 & x + 2 & 5 \\ x + 9 & 3 & x + 4\end{vmatrix} \left[\text{ Applying }C_1 = C_1 + C_2 + C_3 \right]\] 

\[ = \left( x + 9 \right)\begin{vmatrix}1 & 3 & 5 \\ 1 & x + 2 & 5 \\ 1 & 3 & x + 4\end{vmatrix} \] 

\[ = \left( x + 9 \right)\begin{vmatrix}1 & 3 & 5 \\ 0 & x - 1 & 0 \\ 1 & 3 & x + 4\end{vmatrix} \left[\text{ Applying }R_2 \text{ to } R_2 - R_1 \right]\] 

\[ = \left( x + 9 \right)\begin{vmatrix}1 & 3 & 5 \\ 0 & x - 1 & 0 \\ 0 & 0 & x - 1\end{vmatrix} \left[\text{ Applying }R_3 \text{ to } R_3 - R_1 \right]\] 

\[ ∆ = \left( x + 9 \right) \left( x - 1 \right)^2 = 0\] 

\[x = - 9, 1, 1\]

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Chapter 6: Determinants - Exercise 6.2 [Page 61]

APPEARS IN

RD Sharma Mathematics [English] Class 12
Chapter 6 Determinants
Exercise 6.2 | Q 52.5 | Page 61

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