Question

dada a p.a. (18,12,6,0,-6,-12 ...),calcule o 16 termo

Answer 1

Dados :
>>>>>>>
a1 = 18
a2 = 12
n = 16
r = a2 - a1 > r = 12 - 18 > r = - 6
an = a16 = ?

Formula :
=========
an = a1 + ( n - 1 ) x r
a16 = 12 + ( 16 - 1 ) x (-6)
a16 = 12 + ( 15 x (-6))
a16 = 12 + (-90)
a16 = 12 - 90
a16 = - 72