Respuesta :

9514 1404 393

Answer:

  an = 2(-4)^(n-1)

Step-by-step explanation:

The general form of the explicit formula for a geometric series with first term a1 and common ratio r is ...

  an = a1·r^(n-1)

Your sequence has a1=2 and r=-8/2 = -4. So, the explicit formula is ...

  an = 2(-4)^(n-1)