Question

considere as sequencias (1,3,5,7...) forma geral an=a1+a1(n-1).r

Answer 1

a1 = 1
a2 = 3

r = a2 - a1
r = 3 - 1
r = 2

an = a1 + (n - 1) . r
an = 1 + (n - 1) . 2
an = 1 + 2n - 2
an = 2n - 1