Question

calcule o numero de termos da p.g (9,3,1,...,1/81)

Answer 1

a1 = 9
a2= 3
q = 3/9 = 1/3 *****
an = 1/81
n = ?

1/81 = 9/1* (1/3)ⁿ⁻¹
(1/3)ⁿ⁻¹ = 1/81 : 9/1  = 1/81 * 1/9 = 1/ 729 =( 1/3)⁶
( 1/3)ⁿ⁻¹  = ( 1/3)⁶
n - 1 = 6
n = 6 + 1
n = 7 ***