Question

Determine as variáveis
3x+y=12
X-y=4

Answer 1

$\Large\boxed{\begin{array}{l}+\underline{\begin{cases}\sf 3x+y=12\\\sf x-y=4\end{cases}}\\\sf 4x=16\\\sf x=\dfrac{16}{4}\\\\\sf x=4\\\sf x-y=4\longrightarrow y=x-4\\\sf y=4-4\\\sf y=0\\\sf \\\sf S=\{4,0\}\end{array}}$