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The first and ninth terms of an arithmetic sequence are 2/3 and- 4/5, respectively. What is the fifth term?

 Jun 1, 2021
 #1
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We  can find  the  common difference, d,  as

 

(2/3)  +  d (8)  =     -4/5

 

d(8)  =  -4/5  - 2/3

 

8d  =  -  (12  + 10)  /  15   = -22/15

 

d  =  -22/ (15 * 8)  =   -22/120   =  -11/60

 

So....the  5th term is

 

2/3  -  (11/60 ) (4)  = 

 

2/3  -  44/60    =

 

2/3  - 11/15   =

 

10/15   -11/15  = 

 

-1/15

 

 

cool cool cool

 Jun 1, 2021

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