Question

resolva sistema -4x+3y= 30 4x+2y=5

Answer 1

Podemos resolver utilizando o método da adição:

$\left \{ {{-4x~+~3y~=~30} \atop {~4x~+~2y~=~5}} \right.$

Somando as duas equações:

$(-4x+3y)~+~(4x+2y)~=~30~+~5\\\\\\-4x+4x+3y+2y~=~35\\\\\\5y~=~35\\\\\\y~=~\frac{35}{5}\\\\\\\boxed{y~=~7}\\\\\\Substituindo~y~em~qualquer~uma~das~duas~equacoes~para~achar~x:\\\\\\4x+2y~=~5\\\\\\4x+2~.~7~=~5\\\\\\4x~=~5-14\\\\\\4x~=~-9\\\\\\\boxed{x~=~-\frac{9}{4}}$

Resposta:      (x,y) = (-9/4  ,  7)