Question

encontre o valor de x e Y

(x-y=5 )
(x+y=20)​

Answer 1

Resposta:

$\left \{ {{x-y=5} \atop {x+y=20}} \right.$

$\left \{ {{x=5+y} \atop {5+2y=20}} \right.$

$\left \{ {{x=5+y} \atop {y=\frac{15}{2} }} \right.$

$\left \{ {{x=\frac{10+15}{2} } \atop {y=\frac{15}{2} }} \right.$

$\left \{ {{x=\frac{25}{2} } \atop {y=\frac{15}{2} }} \right.$