Question

determine o decimo quinto termo finito da PA(3,6,9...,)

Answer 1

15} = ?
P.A.(3,6,9....)
r = a 2 - a 1
r = 6 - 3
r = 3
a 15 = a 1 + (n - 1 ).r
a 15 = 3 + (15 - 1 ). 3
a 15 = 3 + 14.3
a 15 = 3 + 42
a 15 = 45