Question

An=999 A1= 108 r=9 n?​

Answer 1

an = a1 + (n - 1).r

r.(n - 1) = an - a1

9n - 9 = 999 - 108

9n = 999 - 108 + 9

9n = 900

n = 900/9

n = 100

Resposta: 100

Answer 2

An = 999

A1 = 108

r = 9

n?​

an = a1  + r*)n - 1)

999 = 108 + 9n - 9

9n = 999 + 9 - 108 = 900

n = 100 termos