Question

sabendo que a+b=13ea2-b2=39 calcule o valor de a

Answer 1

$a^2-b^2=(a+b)(a-b)=13(a-b)=39\Leftrightarrow$

$a-b=3$.

$\left\{\begin{array}{ll}a+b=13\\a-b=3\end{array}\right$

$\Rightarrow S_{(a,\: b)}=\{(8,\: 5)\}$.