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The ninth and tenth terms of an arithmetic sequence are 1/4 and -1/3, respectively. What is the second term?

 Apr 11, 2022

Best Answer 

 #2
avatar+124594 
+1

We have an arithmetic series

 

The common difference is      -1/3 - 1/4  =   - 7/12

 

So we have

 

a9 =  a2 + (-7/12) ( 7)

 

1/4 =   a2  -  49/12

 

3/12  = a2 - 49/12

 

(49 + 3)  /12  =  a2

 

52 /12  = a=  13/3

 

cool cool cool

 Apr 11, 2022
 #1
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0

Find common ratio to be   - 4/3

 

then    x2 ( -4/3)7  = 1/4       shows  x2 = - 2187/65536

 Apr 11, 2022
 #2
avatar+124594 
+1
Best Answer

We have an arithmetic series

 

The common difference is      -1/3 - 1/4  =   - 7/12

 

So we have

 

a9 =  a2 + (-7/12) ( 7)

 

1/4 =   a2  -  49/12

 

3/12  = a2 - 49/12

 

(49 + 3)  /12  =  a2

 

52 /12  = a=  13/3

 

cool cool cool

CPhill Apr 11, 2022

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