Respostas

2014-03-30T09:31:59-03:00
(5y+4y)2 - (5y-4y)2
(9y)2 - (1y)2
81y - 1y
80y
2014-03-30T10:13:17-03:00
(5y+4y)2-(5y-4y)2
(9y)-2(1y)2
81y-1y