Question

Encontre a soma dos 50 primeiros termos de 1,3,5,70

Answer 1

P.A.(1,3,5,7,...)
r = a 2 - a 1
r = 3 - 1
r = 2
a 50 = a 1 + (n - 1 ).2
a 50 = 1 + (50 - 1 ).2
a 50 = 1 + 49 . 2
a 50 = 1 + 98
a 50 = 99
S 50 = 50 . (a 1 + a 50) / 2
S 50 = 50 .(1 + 99) / 2
S 50  = 50 . 100 / 2
S 50 = 5000 / 2
S 50 = 2500