Question

determine o 6º termo da p.g infinita (10,4, 8/5...)

Answer 1

a1 = 10
a2 = 4
q = a2/a1 => q = 4/10 => q = 2/5
n = 6
an = ?

an = a1 . q^(n-1)
a6 = 10 . (2/5)^(6-1)
a6 = 10. (2/5)^5
a6 = 10 . 32/3125
a6 = 320/3125
a6 = 64/625

Answer 2

Pelo Termo Geral: 

q=a₂/a₁=4/10

an=a₁*qⁿ⁻¹ ⇒ a6=10*(4/10)⁶⁻¹ ⇒ a6=10*(4/10)⁵ ⇒ a6=10*4⁵/10⁵ ⇒ a6=4⁵/10⁴