Minta tolong yaaa yg nomor 9.. Matematika Aku sdh ngitung, tapi gak ada jawabannya

Kelas : XI SMA
Mapel : Matematika Wajib
Bab : Matriks
Indikator : Persamaan Matriks

Langkah Penyelesaian dan Jawaban :
XA = B
X = BA⁻¹

- Mencari invers :

[tex]A = \left[\begin{array}{ccc}1&-3\\2&1\end{array}\right] \\\\ A^{-1} = \frac{1}{1 - (- 6)} \left[\begin{array}{ccc}1&3\\-2&1\end{array}\right] \\\\ A^{-1} = \frac{1}{7} \left[\begin{array}{ccc}1&3\\-2&1\end{array}\right] \\\\ A^{-1} = \left[\begin{array}{ccc} \frac{1}{7} & \frac{3}{7} \\- \frac{2}{7} & \frac{1}{7} \end{array}\right][/tex]

- Mencari x :

[tex]A^{-1} = \left[\begin{array}{ccc} \frac{1}{7} & \frac{3}{7} \\- \frac{2}{7} & \frac{1}{7} \end{array}\right] \\\\ x = \left[\begin{array}{ccc}4&-5\\-4&-2\end{array}\right] \left[\begin{array}{ccc} \frac{1}{7} & \frac{3}{7} \\- \frac{2}{7} & \frac{1}{7} \end{array}\right] \\\\ x = \left[\begin{array}{ccc} \frac{4}{7} + \frac{10}{7} & \frac{12}{7} - \frac{5}{7} \\ - \frac{4}{7} + \frac{4}{7} & - \frac{12}{7} - \frac{2}{7} \end{array}\right] \\\\[/tex]

[tex] x = \left[\begin{array}{ccc}2&1\\0&- 2\end{array}\right] [/tex]