Question

qual o n de termos da pa (9,12,........,60)?

Answer 1

P.A ( 9,12,----, 60)

n = ?

r= a2 - a1 = 12 - 9 = 3

An = a1 + ( n - 1) x r

An = 60

60 = 9 + ( n - 1) x 3
60= 9 + 3n - 3
3n = 60 - 9 + 3
3n = 54
n = 54/3
n = 18