Question

4) Quantos termos tem a P.A. (5, 9, 13,...,37)​

Answer 1

an= a1 + (n - 1) • r

an= 37

a1= 5

n= ?

r= 9 - 5 = 4

37= 5 + (n - 1) • 4

37= 5 + 4n - 4

37= 1 + 4n

37 - 1 = 4n

36= 4n

n= 36/4

n= 9