Respostas

2014-08-26T17:23:25-03:00
De forma geral:

(a + b)² = a² +2.a.b + b²

No caso:

(x+\frac{y}{3})^2 = x^2+2.x.\frac{y}{3} + \frac{y^2}{9} \\ \\ \boxed{x^2+\dfrac{2.x.y}{3}+\dfrac{y^2}{9}}