Question

Alguém sabe? por favor?
2x + 3y = 7
3x + 5y = 13

Answer 1

$\begin{bmatrix}2x+3y=7\\ 3x+5y=13\end{bmatrix}\\\\2x+3y-3y=7-3y$

$2x=7-3y\\\\\frac{2x}{2}=\frac{7}{2}-\frac{3y}{2}\\\\x=\frac{7-3y}{2}$

$\begin{bmatrix}3\cdot \frac{7-3y}{2}+5y=13\end{bmatrix}\\\\\frac{21+y}{2}=13\\\\\begin{bmatrix}\frac{21+y}{2}=13\end{bmatrix}\\\\\frac{21+y}{2}=13\\\\\frac{2\left(21+y\right)}{2}=13\cdot \:2\\\\21+y=26\\\\21+y-21=26-21\\\\y=5$

$x=\frac{7-3\cdot \:5}{2}\\\\x=-4\\\\x=-4,\:y=5$