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The first and thirteenth terms of an arithmetic sequence are 7/9 and 1/3, respectively. What is the seventh term?

 Dec 23, 2020
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We have that

 

1/3  =  7/9  +  d (13 - 1)

 

1/3  = 7/9  +  12d

 

(1/3 - 7/9)  =12 d

 

(3/9 - 7/9)  = 12 d

 

-4/9  = 12 d      divide both sides  by  12

 

-4/ 9  *  1/12   = d

 

-4/108  =d

 

-1/27    = d

 

To find the seventh term we have

 

7/9  +  (-1/27) (7 -1)

 

7/9 + (-1/27) (6)

 

7/9  -6/27  = 

 

7/9 - 2/9  = 

 

   5/9

 

 

 

 

cool cool cool

 Dec 23, 2020

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