+0  
 
0
103
2
avatar+95 

1. What is the explicit rule for the geometric sequence? 120, 40, 40/3, 40/9, 40/27, ...

2. What is the recursive rule for the geometric sequence? 10, −80, 640, −5120, ...

-
Thank you to anyone who helps!

Jaleco  Mar 13, 2018
Sort: 

2+0 Answers

 #1
avatar
+2

The first one is:

Multiply each term by 1/3, so you have:

120, [120x1/3] =40, [40x1/3]=40/3, [40/3x1/3]=40/9...........and so on.

 

The second one is:

Multiply each term by -8, so you have:

10, [-8x10]=-80, [-80x-8]=640, [640x-8] =-5120........and so on.

Guest Mar 13, 2018
 #2
avatar+12266 
+2

The EXPLICIT formula for the first one:

 

r = 1/3    a1 = 120

 

an = a1 * 1/3^(n-1)

 

The RECURSIVE formula for the second one is

 

r = -8  

 

an = a(n-1) * (-8) 

ElectricPavlov  Mar 13, 2018
edited by Guest  Mar 13, 2018

22 Online Users

avatar
avatar
avatar
avatar
New Privacy Policy (May 2018)
We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  Privacy Policy