Question

se xy = 1/3 ,qual o valor de (x+y)² - (x - y)²

Answer 1

$(x+y)^2-(x-y)^2=x^2+2xy+y^2-x^2+2xy-y^2=4xy\\ \\ xy=\frac{1}{3} \rightarrow 4xy=4*\frac{1}{3}=\frac{4}{3}$