Use the formula for the sum of an AP: , where:

 = Sum of the 1st 10 terms (, in this case)

  = Number of terms (10, in this case)

 = 1st term (11, in this case)

 = Value of last term (38, in this case) 

Answer by ikleyn(52781)   (Show Source): You can put this solution on YOUR website!
 .

How to find the sum of the first 10 terms of each arithmetic sequence?



 1. a(sub1) = 11 and a(sub10) = 38



 2. a (sub1) = 10 and a(sub10) = 55

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~





1.  Use the formula for the sum of an arithmetic progression

     = :    =  =  = 24.5*10 = 245.

    You do not need to calculate the common difference in this case.



2.  Do THE SAME:

     = :    =  =  =  = 32.5*10 = 325.

    Again, you do not need to calculate the common difference in this case.






See introductory lessons on arithmetic progressions in this site



    - Arithmetic progressions (*)



    - The proofs of the formulas for arithmetic progressions (*)



    - Problems on arithmetic progressions  



    - Word problems on arithmetic progressions



    - Mathematical induction and arithmetic progressions



    - One characteristic property of arithmetic progressions



    - Solved problems on arithmetic progressions 





The lessons marked (*) contain the formulas to sum arithmetic progression: read them very attentively.





Also,  you have this free of charge online textbook in ALGEBRA-II in this site



    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.





The referred lessons are the part of this online textbook under the topic "Arithmetic progressions".







 

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