Jawabanmu

2014-06-13T14:39:45+07:00
  \left[\begin{array}{cc}4&-3&\\2&-5\\\end{array}\right]   \left[\begin{array}{c}x&y\\\\\end{array}\right]   \left[\begin{array}{c}-3&9\\\\\end{array}\right]

x - y = ?

Jwb : klo perkalian matriks, ingat BARIS X KOLOM, atau horizontal x vertikal
Jadi, kita bisa masukkan hasil perkaliannya.

1.  4x -3y = -3
2   2x - 5y = 9

Eliminasi salah satu, 

1.  4x -3y = -3 .... x1
2   2x - 5y = 9 .... x2
__________________ -

1. 4x - 3y = -3
2. 4x - 10y = 18
__________________ - 
          7y = -21
           y = -3

4x - 3y = -3
4x - 3(-3) = -3
4x +9 = -3
4x = -3 - 9
4x = -12
x = -3

=> x - y = -3 - (-3) = 0