Question

aflati urmatorul termen din sirul 4,13,31,67 repede va rog !;-) ;-)

Answer 1

139, sper ca te-am ajutat.

regula:
uite - 13-4=9
31-13=18(9×2)
67-31=36(18×2)
139-67=72(36×2)
ai inteles?

Answer 2

4, 13, 31, 67

13 = 4 + 9
31 = 13 + 2·9
67 = 31 + 2·(2·9)
x = 67 + 2·(2·2·9)

=> x = 67 + 8·9 => x = 67 + 72 => x = 139