Saya sudah menjawab namun ragu.. Jawaban saya a = 2 , b = -1 Bener ga kak..

Materi : Matriks
Bahasan : Persamaan Linear dengan Matriks
Jawaban : a = 6 dan b = - 3

Langkah - langkah :
[tex] N^{-1} = \frac{1}{(7.3) - ((-5)(-4))} \left[\begin{array}{ccc}3&4\\5&7\end{array}\right] \\ \\ N^-1 = \left[\begin{array}{ccc}3&4\\5&7\end{array}\right] \\ \\ \left[\begin{array}{ccc}3&4\\5&7\end{array}\right] \left[\begin{array}{ccc}a\\b\end{array}\right] = \left[\begin{array}{ccc}6\\9\end{array}\right] [/tex]

Gunakan cara determinan untuk mencari penyelesaian :
[tex]\left[\begin{array}{ccc}3&4\\5&7\end{array}\right] \left[\begin{array}{ccc}a\\b\end{array}\right] = \left[\begin{array}{ccc}6\\9\end{array}\right] \\ \\ a = \frac{det(a)}{det(N^-1)} = \frac{42 - 36}{21 - 20} = \frac{6}{1} = 6 \\ \\ b = \frac{det(b)}{det(N^-1)} = \frac{27 - 30}{21 - 20} = \frac{-3}{1} = - 3 [/tex]