Question

Calcule a equação $\left[\begin{array}{ccc}x&4\\1&2\\\end{array}\right] = 3x - 5$

Answer 1

Usando determinante da matriz
         2x - 4 = 3x - 5
        2x - 3x = - 5 + 4
               - x = - 1
                               x = 1

Answer 2

$\left[\begin{array}{ccc}x&4\\1&2\\\end{array}\right] = 3x - 5\\\\\\ \{x.2\}-\{1.4\}=3x-5\to \\\\2x -4 = 3x - 5\to\\\\ 2x-3x = - 5+ 4\to\\\\ -x = - 1~(-1)\to\\\\ \boxed{x=1}$