$a_n$ and $b_n$ are sequences of arithmetic and geometric means, whose first three terms match. Given some...











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For $n>3$,





  • $a_{n}$ is arithmetic mean of $a_1$ through $a_{n-1}$


  • $b_{n}$ is geometric mean of $b_1$ through $b_{n-1}$


For $i=1,2,3$,





  • ${{a}_{i}}$ = ${{b}_{i}}$


If $a_{1} = 3$, $a_{2017} = 7$, $a_{2018}=8$,
then
$$a_{2}^{2}+a_{3}^{2} = text{?}$$




What is the use of $b$ here? Where is it going to be used in solution?











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    many times i feel we at this site , are very quick to downvote a question. why cant it be possible that a person who is new getting accustomed to site is facjng problem. like i joined two months ago lot of my questions got downvoted. i think we can give newbies some time. question migjt be good
    – maveric
    Nov 18 at 9:29












  • See $2a_3=a_1+a_2$ and $b_3=sqrt{a_1a_2}$ .
    – Yadati Kiran
    Nov 18 at 9:34

















up vote
0
down vote

favorite












For $n>3$,





  • $a_{n}$ is arithmetic mean of $a_1$ through $a_{n-1}$


  • $b_{n}$ is geometric mean of $b_1$ through $b_{n-1}$


For $i=1,2,3$,





  • ${{a}_{i}}$ = ${{b}_{i}}$


If $a_{1} = 3$, $a_{2017} = 7$, $a_{2018}=8$,
then
$$a_{2}^{2}+a_{3}^{2} = text{?}$$




What is the use of $b$ here? Where is it going to be used in solution?











share|cite|improve this question




















  • 1




    many times i feel we at this site , are very quick to downvote a question. why cant it be possible that a person who is new getting accustomed to site is facjng problem. like i joined two months ago lot of my questions got downvoted. i think we can give newbies some time. question migjt be good
    – maveric
    Nov 18 at 9:29












  • See $2a_3=a_1+a_2$ and $b_3=sqrt{a_1a_2}$ .
    – Yadati Kiran
    Nov 18 at 9:34















up vote
0
down vote

favorite









up vote
0
down vote

favorite











For $n>3$,





  • $a_{n}$ is arithmetic mean of $a_1$ through $a_{n-1}$


  • $b_{n}$ is geometric mean of $b_1$ through $b_{n-1}$


For $i=1,2,3$,





  • ${{a}_{i}}$ = ${{b}_{i}}$


If $a_{1} = 3$, $a_{2017} = 7$, $a_{2018}=8$,
then
$$a_{2}^{2}+a_{3}^{2} = text{?}$$




What is the use of $b$ here? Where is it going to be used in solution?











share|cite|improve this question















For $n>3$,





  • $a_{n}$ is arithmetic mean of $a_1$ through $a_{n-1}$


  • $b_{n}$ is geometric mean of $b_1$ through $b_{n-1}$


For $i=1,2,3$,





  • ${{a}_{i}}$ = ${{b}_{i}}$


If $a_{1} = 3$, $a_{2017} = 7$, $a_{2018}=8$,
then
$$a_{2}^{2}+a_{3}^{2} = text{?}$$




What is the use of $b$ here? Where is it going to be used in solution?








sequences-and-series systems-of-equations






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edited Nov 18 at 9:44









Blue

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47k870148










asked Nov 18 at 9:25









Abhinov Singh

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  • 1




    many times i feel we at this site , are very quick to downvote a question. why cant it be possible that a person who is new getting accustomed to site is facjng problem. like i joined two months ago lot of my questions got downvoted. i think we can give newbies some time. question migjt be good
    – maveric
    Nov 18 at 9:29












  • See $2a_3=a_1+a_2$ and $b_3=sqrt{a_1a_2}$ .
    – Yadati Kiran
    Nov 18 at 9:34
















  • 1




    many times i feel we at this site , are very quick to downvote a question. why cant it be possible that a person who is new getting accustomed to site is facjng problem. like i joined two months ago lot of my questions got downvoted. i think we can give newbies some time. question migjt be good
    – maveric
    Nov 18 at 9:29












  • See $2a_3=a_1+a_2$ and $b_3=sqrt{a_1a_2}$ .
    – Yadati Kiran
    Nov 18 at 9:34










1




1




many times i feel we at this site , are very quick to downvote a question. why cant it be possible that a person who is new getting accustomed to site is facjng problem. like i joined two months ago lot of my questions got downvoted. i think we can give newbies some time. question migjt be good
– maveric
Nov 18 at 9:29






many times i feel we at this site , are very quick to downvote a question. why cant it be possible that a person who is new getting accustomed to site is facjng problem. like i joined two months ago lot of my questions got downvoted. i think we can give newbies some time. question migjt be good
– maveric
Nov 18 at 9:29














See $2a_3=a_1+a_2$ and $b_3=sqrt{a_1a_2}$ .
– Yadati Kiran
Nov 18 at 9:34






See $2a_3=a_1+a_2$ and $b_3=sqrt{a_1a_2}$ .
– Yadati Kiran
Nov 18 at 9:34












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See $2a_3=a_1+a_2$, $a_2=a_1$ and $b_3=sqrt{a_1a_2}$. We get $a_2^2+a_3^2=18$.






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    See $2a_3=a_1+a_2$, $a_2=a_1$ and $b_3=sqrt{a_1a_2}$. We get $a_2^2+a_3^2=18$.






    share|cite|improve this answer

























      up vote
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      See $2a_3=a_1+a_2$, $a_2=a_1$ and $b_3=sqrt{a_1a_2}$. We get $a_2^2+a_3^2=18$.






      share|cite|improve this answer























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        up vote
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        down vote









        See $2a_3=a_1+a_2$, $a_2=a_1$ and $b_3=sqrt{a_1a_2}$. We get $a_2^2+a_3^2=18$.






        share|cite|improve this answer












        See $2a_3=a_1+a_2$, $a_2=a_1$ and $b_3=sqrt{a_1a_2}$. We get $a_2^2+a_3^2=18$.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Nov 18 at 9:36









        Yadati Kiran

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