Question

quantos termos tem a p.a (5,9,13.......,37)

Answer 1

an=a1+(n-1)*r
37=5+(n-1)*4
37=5+4n-4
37=4n+1
37-1=4n
36=4n
36/4=n
9=n
9 termos.

Answer 2

an = 37
a1 = 5
n = ?
r = 4

an = a1 + (n - 1)r
37 = 5 + (n - 1)4
37 = 5 + 4n - 4
-4n = -4 + 5 - 37
4n = 36
n = 36/4
n = 9

BONS ESTUDOS!