[tex] \left[\begin{array}{ccc}1&1\\a&2\end{array}\right] [/tex] dikali [tex] \left[\begin{array}{ccc}x\\y\\\end{array}\right] [/tex] =[tex] \left[\begin{arr

[tex] \left[\begin{array}{cc}1&1\\a&2\end{array}\right] [/tex] x [tex] \left[\begin{array}{cc}x + y\\ax + 2y\end{array}\right] [/tex] = [tex] \left[\begin{array}{cc}8\\4\end{array}\right] [/tex]
diperoleh persamaan:
x + y = 8      ...(i)
ax + 2y = 4 ... (ii)
determinan = DU - DS
                 = (2x1) - (1 x a)
 maka (2 x 1) - ( 1 x a ) = 1
             2 - a = 1
                  a = 1
Substitusikan a ke persamaan (ii)
(1)x +  2y = 4 menjadi x + 2y = 4 ...(iii)
Eleminasi (i)(iii)
  x +  y  = 8
  x + 2y = 4  -
       -y = 4
        y  = -4
Substitusikan ke persamaan (i)
  x + y = 8
  x +(-4) = 8
       x = 12

moga membantu ^_^