Question

Enter a recursive rule for the geometric sequence. 5, −10, 20, −40, ... a1= an=

Answer 1

9514 1404 393

Answer:

• a[1] = 5
• a[n] = -2a[n-1]

Step-by-step explanation:

The first term is the first one on the list:

  a[1] = 5

__

The ratio of terms is ...

  -10/5 = -2

That is, each term is -2 times the previous one, so the recursive rule is ...

  a[n] = -2·a[n-1]