Respostas

2013-08-26T17:19:30-03:00
Razão= 1/2

an = a1 + (n - 1).r
a50 = (-1/2) + 49. 1/2
a50 = (-1 + 49) / 2
a50 = 48/2 = 24

Sn = (a1 + an) . n/ 2
S=(-1/2 + 24).50/2
S=47/2.50/2
S=1175/2 = 587,5
12 3 12