Respostas

2013-12-12T09:57:44-02:00
(7a+1) (7a -1)

49a²-7a+7a-1

49a²-1
1 5 1
2013-12-12T10:06:27-02:00

(7a+1)(7a-1)=
49a²-7a+7a-1
49a²-1