Question

Sabendo que x²+y²=50 e xy=10, calcule o valor de (x-y)².

Answer 1

$x^2 + y^2 = 50$
$xy = 10$

$(x - y)^2 = x^2 - 2xy + y^2 \\ \\ (x - y)^2 = x^2 + y^2 - 2xy \\ \\ (x - y)^2 = 50 - 2.10 \\ \\ (x - y)^2 = 50 - 20 \\ \\ (x - y)^2 = 30$