Question

Sabendo que x² - y²=12 e x+y=6 qual é o valor de x-y?

Answer 1

$\begin{array}{l}x^{2} -y^{2} =12\Leftrightarrow ( x+y)( x-y) =12\\\\\text{Mas} \ x+y=6\\\\\therefore 6( x-y) =12\Leftrightarrow x-y=2\end{array}$