Question

Ache a soma dos termos da P.A(-16,-14,-12,...,84)

Answer 1

P.A(-16,-14,-12,...,84)

a1 = -16 

r = -14 - (-16) = -14 + 16 = 2

84 = -16 + (n -1)2
84 = -16 + 2n - 2 
84 = -18 + 2n 
-2n =  -18 - 84 
-2n = -102
n = -102/-2 
n = 51

S51 = [(-16+84)*51]/2 = 68*51/2 = 34*51 = 1734

*-*-*-*-*-*-*-*-*-*-*-*
06/10/2016
Sepauto 
*-*-*-*-*-*-*-*-*-*-*-*