SOLUTION: The 15th term an A.P is 25.find it's first term of its common different is 2

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Question 1128789: The 15th term an A.P is 25.find it's first term of its common different is 2
Answer by ikleyn(52787) About Me  (Show Source):
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The 15th term an A.P is 25. find it's first term highlight%28cross%28of%29%29 if its common highlight%28cross%28different%29%29 difference is 2.
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25 = a%5B15%5D = a%5B1%5D+%2B+2%2A%2815-1%29 = a%5B1%5D%2B2%2A14 = a%5B1%5D%2B28,


which implies 


a%5B1%5D = 25 - 28 = -3.     ANSWER

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For introductory lessons on arithmetic progressions see
    - Arithmetic progressions
    - The proofs of the formulas for arithmetic progressions
    - Problems on arithmetic progressions
    - Word problems on arithmetic progressions
in this site.

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".


Save the link to this textbook together with its description

Free of charge online textbook in ALGEBRA-II
https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson

into your archive and use when it is needed.


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