Question

X-y= 5
X+y = 1

........

Answer 1

$\begin{cases}{x - y = 5} \\ x + y = 1\end{cases}$

Eliminação de Gauss:

$\left[ \begin{array}{ccc}1 & - 1 & 5\\1 & 1 & 1\end{array} \right]$

$\left[ \begin{array}{ccc}1 & - 1 & 5\\0 & 2 & -4\end{array} \right]$

$\left[ \begin{array}{ccc}1 & - 1 & 5\\ 0 & 1 & - 2\end{array} \right]$

$\left[ \begin{array}{ccc}1 & 0& 3\\0 & 1& - 2\end{array} \right]$

$\begin{cases}{x = 3} \\ y = - 2\end{cases} \\ \\ (x \: , \:y) = ( 3 \: , \: - 2)$