Question

Preciso resolver essa equação
3x+2y=70
-x+3y=25

Answer 1

Para resolver o sistema apresentado, podemos utilizar qualquer método conhecido. Vou utilizar o método da substituição.

$Isolando~"x"~na~2^a~equacao:\\\\\\-x+3y~=~25\\\\\\-x~=~25-3y\\\\\\\boxed{x~=~3y-25}\\\\\\Substituindo~na~1^a~equacao:\\\\\\3~.~(3y-25)+2y~=~70\\\\\\9y-75+2y~=~70\\\\\\11y~=~70+75\\\\\\\boxed{y~=~\frac{145}{11}}\\\\\\Substituindo~o~valor~de~y~em~uma~das\\equacoes~para~achar~"x":\\\\\\x~=~3y-25\\\\\\x~=~3~.~\left(\frac{145}{11}\right)-25\\\\\\x~=~\frac{435}{11}-25\\\\\\x~=~\frac{1~.~435~-~11~.~25}{11}\\\\\\\boxed{x~=~\frac{160}{11}}$