Question

Numa pg o 1 termo e 3 eo ultimo e 1875.se a raza e 5 qual e o numero de termos dessa pg?

Answer 1

a1= 3
an= 1875
 an= a1 · q^n-1
1875=3·5^n-1
1875/3=5^n-1
625=5^n-1
5^4=5^n-1
4=n-1
n= 5