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What is the first term if the 10th term of an arithmetic sequence is 39 and the 15th term is 59

 Nov 15, 2021
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What is the first term if the 10th term of an arithmetic sequence is 39 and the 15th term is 59

 

Use the formula for the nth term:

 

39 ==F  +  9D...................(1), where F==First term,  D==Common difference

59 ==F  +  14D..................(2), solve for F, D

 

Use substitution to get:

F==3   and   D == 4

 

Your sequence looks like this:

3 , 7 , 11 , 15 , 19 , 23 , 27 , 31 , 35 , 39 , 43 , 47 , 51 , 55 , 59 , >>Number of terms = 15>>Total Sum == 465

 Nov 15, 2021

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