[tex]X= \left[\begin{array}{ccc}a&b\\c&d\\\end{array}\right] [/tex]
[tex] \left[\begin{array}{ccc}a&b\\c&d\\\end{array}\right] * \left[\begin{array}{ccc}-1&2\\3&4\\\end{array}\right] = \left[\begin{array}{ccc}5&10\\4&2\\\end{array}\right] [/tex]
-a+3b=5
2a+4b=10
-c+3d=4
2c+4d=2
-a+3b=5 =>-a+3b=5
2a+4b=10|:2 a+2b=5
5b=10 =>b=2
a+4=5 =>a=1
-c+3d=4
c+2d=1
5d=5 =>d=1
c+2=1 =>c= -1
[tex] X= \left[\begin{array}{ccc}1&2\\-1&1\\\end{array}\right] [/tex]
