Respostas

2014-03-08T18:06:23-03:00
(a - b) ³ = a³  -3a²b +3ab² - b³ , então basta aplicarmos isto a conta:

(a - 4b) ³ = ( a - 4b) ². ( a - 4b) =  (a² - 2.a.4b + 4b²)(a - 4b)--->
a³ -4a²b - 8a²b + 32ab² + 4ab² -16b³ ---->
a³ -12a²b + 36ab² - 16b³
4 4 4