Question

Quantos termos tem a P.A. (9, 13, 17...,41) ? *

a)8

b)9

c)6

d)7

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Answer 1

an = a1 + (n - 1).r

r = 13 - 9

r = 4

41 = 9 + (n -1).4

41 - 9 = 4n - 4

32 = 4n - 4

4n = 32 + 4

4n = 36

n = 36/4

n = 9 termos

Alternativa B