ada yang bisa bantu??

Penyelesaian:

AB^-1 = [tex] \left[\begin{array}{cc}3/8&-1/2\\-1/8&1/2\end{array}\right] [/tex]
B^-1 = [tex] \left[\begin{array}{cc}1/4&1/8\\1/4&-3/8\end{array}\right] [/tex]

A. B^-1 = A.B^-1

Misal: A = [tex] \left[\begin{array}{cc}a&b\\c&d\end{array}\right] [/tex]

[tex]\left[\begin{array}{cc}a&b\\c&d\end{array}\right] \left[\begin{array}{cc}1/4&1/8\\1/4&-3/8\end{array}\right] = \left[\begin{array}{cc}3/8&-1/2\\-1/8&1/2\end{array}\right][/tex]
lakukan perkalian matriks, didapat:

1/4 a + 1/4 b = 3/8
2a + 2b = 3  (1)

1/8 a - 3/8 b = -1/2
a - 3b = -4  (2)

1/4 c + 1/4 d = -1/8
2c + 2d = -1  (3)

1/8 c - 3/8 d = 1/2
c - 3d = 4  (4)

eliminasi persamaan (1) dan (2):
2a + 2b = 3    x1
a - 3b = -4      x2
-----------------   -
b = 11/8 ; a = 1/8

eliminasi persamaan (3) dan (4):
2c + 2d = -1    x1
c - 3d = 4        x2
------------------   -
d = -9/8 ; c = 5/2

didapat matrik A = [tex]\left[\begin{array}{cc}1/8&11/8\\5/2&-9/8\end{array}\right][/tex]