Question

Calcular soma dos termos da PA (-16, -14, -12 ,..., 84)

Answer 1

a1 = -16
a2 = -14
r = -14 - ( -16) = -14 + 16 = 2 ****
an = 84

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

S51 = ( -16 + 84) * 25.5
S51 = 68 * 25.5 =1734 *****