Odpowiedzi

2010-03-29T21:05:23+02:00
Zad 2
a3 = 45 = a1 * q^2
a6 = 1215 = a3 * q^3
45* q^3 = 1215 <=> q^3 = 27 <=> q = 3
45 = a1 * q^2 <=> 45 = a1 * 9 <=> a1 = 5
wzor na n elementów ciągu geom. to Sn = a1 * q^(n-1) więc:
S8 = 5 * 3^(8-1) = 10935

licze na naj:)
2 5 2