Question

Determine o valor de x.y sabendo que (x+y)^2=25 e x^2+y^2=5

Answer 1

Olá, Selfiew.

$\underbrace{(x+y)^2}_{=25}=\underbrace{x^2+y^2}_{=5}+2xy\Rightarrow 25=5+2xy\Rightarrow 2xy=20\Rightarrow\boxed{xy=10}$