Matriks x itu rumus nya gimana?

rumusnya x=B dikali A invers

Materi : Matriks
Bahasan : Persamaan Matriks
Jawaban : E

Langkah - langkah :
Matriks A : [tex] \left[\begin{array}{ccc}2&1\\-3&-1\end{array}\right] [/tex]
A^-1 = [tex] \frac{1}{-2+3} \left[\begin{array}{ccc}-1&-1\\3&2\end{array}\right] = \left[\begin{array}{ccc}-1&-1\\3&2\end{array}\right][/tex]
Matriks B : [tex] \left[\begin{array}{ccc}12&5\\7&3\end{array}\right] [/tex]
X = BA^-1
X = [tex] \left[\begin{array}{ccc}12&5\\7&3\end{array}\right] \left[\begin{array}{ccc}-1&-1\\3&2\end{array}\right] \\ \\ \left[\begin{array}{ccc}(-12 + 15)&(-12 + 10)\\(-7 + 9)&(-7+6)\end{array}\right] = \left[\begin{array}{ccc}3&-2\\2&-1\end{array}\right][/tex]