Question

sendo a1=5 e r=6, calcule a soma dos 16 primeiros termos dessa p.a.

Answer 1

a1 = 5; r = 6; n = 16
an = ?

an = a1 + (n - 1)r
an = 5 + (16 - 1)6
an = 5 + 15*6
an = 5 + 90
an = 95

S = [(a1 + an) / 2]n
S = [(5 + 95) /2]*16
S = [100/2] * 16
S = 50 * 16
S = 800