Resolvamos:
Datos : Fórmula : an= a1*(r)^(n-1)
a1 = 1000 a4 = 1000*(r)^(4-1)
a4 = 8 8/1000 = r^(3)
r = ? (2/10)^3 = r^(3)
S5 = ? RecuerDa: "Bases Iguales , Exponentes Iguales"
r = 2/10
r = 1/5
Ahora hallemos la Sumatoria de los 5 primeros términos (S5) :
Datos : Fórmula : Sn = [ a1*(1-r^n)]/(1-r)
a1 = 1000 S5 = 1000*[1-(1/5)^5]/(1 -(1/5))
r = 1/5 S5 = 1000*[1-(1/3125)]/(4/5)
n = 5 S5 = 1000*(3124/3125)/(4/5)
S5 = ?? S5 = 1000*(3124*5)/(3125*4)
S5 = 1000*(781)/625
S5 = 40*(781)/25
S5 = 8*(781)/5
S5 = 6248/5
SaLuDos :)'
