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Find the Inverse by Using Elementary Row Transformations: ⎡ ⎢ ⎣ 1 2 0 2 3 − 1 1 − 1 3 ⎤ ⎥ ⎦ - Mathematics

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प्रश्न

Find the inverse by using elementary row transformations:

\[\begin{bmatrix}1 & 2 & 0 \\ 2 & 3 & - 1 \\ 1 & - 1 & 3\end{bmatrix}\]

बेरीज

उत्तर

\[A = \begin{bmatrix}1 & 2 & 0 \\ 2 & 3 & - 1 \\ 1 & - 1 & 3\end{bmatrix}\]
We know
\[A = IA \]
\[ \Rightarrow \begin{bmatrix}1 & 2 & 0 \\ 2 & 3 & - 1 \\ 1 & - 1 & 3\end{bmatrix} = \begin{bmatrix}1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1\end{bmatrix} A\]
\[ \Rightarrow \begin{bmatrix}1 & 2 & 0 \\ 0 & - 1 & - 1 \\ 0 & - 3 & 3\end{bmatrix} = \begin{bmatrix}1 & 0 & 0 \\ - 2 & 1 & 0 \\ - 1 & 0 & 1\end{bmatrix} A \left[\text{ Applying }R_2 \to R_2 - 2 R_1\text{ and }R_3 \to R_3 - R_1 \right]\]
\[ \Rightarrow \begin{bmatrix}1 & 2 & 0 \\ 0 & 1 & 1 \\ 0 & - 3 & 3\end{bmatrix} = \begin{bmatrix}1 & 0 & 0 \\ 2 & - 1 & 0 \\ - 1 & 0 & 1\end{bmatrix} A \left[\text{ Applying }R_2 \to - R_2 \right]\]
\[ \Rightarrow \begin{bmatrix}1 & 0 & - 2 \\ 0 & 1 & 1 \\ 0 & 0 & 6\end{bmatrix} = \begin{bmatrix}- 3 & 2 & 0 \\ 2 & - 1 & 0 \\ 5 & - 3 & 1\end{bmatrix} A \left[\text{ Applying }R_1 \to R_1 - 2 R_2\text{ and }R_3 \to R_3 + 3 R_2 \right]\]
\[ \Rightarrow \begin{bmatrix}1 & 0 & - 2 \\ 0 & 1 & 1 \\ 0 & 0 & 1\end{bmatrix} = \begin{bmatrix}- 3 & 2 & 0 \\ 2 & - 1 & 0 \\ \frac{5}{6} & - \frac{1}{2} & \frac{1}{6}\end{bmatrix} A \left[\text{ Applying }R_3 \to \frac{1}{6} R_3 \right]\]
\[ \Rightarrow \begin{bmatrix}1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1\end{bmatrix} = \begin{bmatrix}- \frac{4}{3} & 1 & \frac{1}{3} \\ \frac{7}{6} & - \frac{1}{2} & \frac{- 1}{6} \\ \frac{5}{6} & - \frac{1}{2} & \frac{1}{6}\end{bmatrix}A \left[\text{ Applying }R_1 \to R_1 + 2 R_3\text{ and }R_2 \to R_2 - R_3 \right]\]
\[ \therefore A^{- 1} = \begin{bmatrix}- \frac{4}{3} & 1 & \frac{1}{3} \\ \frac{7}{6} & - \frac{1}{2} & \frac{- 1}{6} \\ \frac{5}{6} & - \frac{1}{2} & \frac{1}{6}\end{bmatrix}\]

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पाठ 7: Adjoint and Inverse of a Matrix - Exercise 7.2 [पृष्ठ ३४]

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आरडी शर्मा Mathematics [English] Class 12
पाठ 7 Adjoint and Inverse of a Matrix
Exercise 7.2 | Q 10 | पृष्ठ ३४

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