Question

Resolva a equação

|X+1 2 3 | |4 1|
| X 1 5 |= |x -2|
| 3 1-2 |

Answer 1

Olá Ravilla,

aplique a regra de Sarrus no determinante de ordem 3 e no de ordem 2 subtraia o produto do elementos da diagonal secundária, do da diagonal principal:

$\left|\begin{array}{ccc}x+1&~~2&3\\x&~~1&5\\3&1&-2\end{array}\right| = \left|\begin{array}{ccc}4&1\\x&-2\\\end{array}\right|\\\\\\ \left|\begin{array}{ccc}x+1&2&3\\x&1&5\\3&1&-2\end{array}\right| \left\begin{array}{ccc}x+1&2\\x&1\\3&1\end{array}\right=4\cdot(-2)-x\cdot1$

$-2x-2+30+3x-9-5x-5+4x=-8-x\\ -x=22\\\\ x=-22$

Tenha ótimos estudos ;D