Chapter 6, Matrices and Determinants - Section 6.3 - Inverses of Matrices and Matrix Equations - 6.3 Exercises - Page 523: 13

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We find the determinant $-26+25 = -1 $ Use the formula \[ M=\frac{1}{ad-bc} \left[ {\begin{array}{cc} d &-b \\ -c & a \\ \end{array} } \right] \] to get \[ M= \left[ {\begin{array}{cc} 13 & 5 \\ -5 & -2 \\ \end{array} } \right] \]