SOLUTION: find missing number 15,45,?,405. note: i know the missing number is 35 but how it is possible, calculated??

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Question 1105397: find missing number 15,45,?,405.
note: i know the missing number is 35 but how it is possible, calculated??
Answer by ikleyn(52788) About Me  (Show Source):
You can put this solution on YOUR website!
.
What you see is a geometric progression with the first term 15 and the common ratio of 3.


The missed number is 135 = 45*3  (and not 35).

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On geometric progression see introductory lessons
    - Geometric progressions
    - The proofs of the formulas for geometric progressions
    - Problems on geometric progressions
    - Word problems on geometric progressions
    - One characteristic property of geometric progressions
    - Solved problems on geometric progressions
    - Fresh, sweet and crispy problem on arithmetic and geometric progressions


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 "Geometric 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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