finding a closed formula to an expression and prove it by inductionInduction to prove a simple formula for calculating the $n$-th derivative?closed form solution for summation of $log(i)$maclaurin series and induction over binomial theoremProve by Induction using Baseline and splitting into LHS & RHS?Improper integral $int_0^inftyfracx^nx^m+n+1 dx=fracn! (m-1)!(m+n)!.$Proving a partial sum with inductionShow that $pi =4-sum_n=1^infty frac(n)!(n-1)!(2n+1)!2^n+1$Induction Proof of Taylor Series FormulaProve $sum_i=1^n(-1)^i(i-1)/2$ is boundedFinding inverse using quadratic formula

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finding a closed formula to an expression and prove it by induction


Induction to prove a simple formula for calculating the $n$-th derivative?closed form solution for summation of $log(i)$maclaurin series and induction over binomial theoremProve by Induction using Baseline and splitting into LHS & RHS?Improper integral $int_0^inftyfracx^nx^m+n+1 dx=fracn! (m-1)!(m+n)!.$Proving a partial sum with inductionShow that $pi =4-sum_n=1^infty frac(n)!(n-1)!(2n+1)!2^n+1$Induction Proof of Taylor Series FormulaProve $sum_i=1^n(-1)^i(i-1)/2$ is boundedFinding inverse using quadratic formula













0












$begingroup$


Let 𝑎 > 0, find a closed formula (no sigmas) for



$$sum_i=1^log_a n a^i $$



i found this formula:
$$ fraca(n-1)a-1$$
but i have trouble proving by induction
i dont really understand what is the base case, the hypothesis and the step
please help, thanks










share|cite|improve this question







New contributor




Exposed is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$







  • 1




    $begingroup$
    Use formula for sum of first k terms of geometric progression where k=log_a(n)
    $endgroup$
    – Vladislav
    Mar 11 at 19:24










  • $begingroup$
    What is exactly the upper summation limit?
    $endgroup$
    – user
    Mar 11 at 19:38















0












$begingroup$


Let 𝑎 > 0, find a closed formula (no sigmas) for



$$sum_i=1^log_a n a^i $$



i found this formula:
$$ fraca(n-1)a-1$$
but i have trouble proving by induction
i dont really understand what is the base case, the hypothesis and the step
please help, thanks










share|cite|improve this question







New contributor




Exposed is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$







  • 1




    $begingroup$
    Use formula for sum of first k terms of geometric progression where k=log_a(n)
    $endgroup$
    – Vladislav
    Mar 11 at 19:24










  • $begingroup$
    What is exactly the upper summation limit?
    $endgroup$
    – user
    Mar 11 at 19:38













0












0








0





$begingroup$


Let 𝑎 > 0, find a closed formula (no sigmas) for



$$sum_i=1^log_a n a^i $$



i found this formula:
$$ fraca(n-1)a-1$$
but i have trouble proving by induction
i dont really understand what is the base case, the hypothesis and the step
please help, thanks










share|cite|improve this question







New contributor




Exposed is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$




Let 𝑎 > 0, find a closed formula (no sigmas) for



$$sum_i=1^log_a n a^i $$



i found this formula:
$$ fraca(n-1)a-1$$
but i have trouble proving by induction
i dont really understand what is the base case, the hypothesis and the step
please help, thanks







calculus






share|cite|improve this question







New contributor




Exposed is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|cite|improve this question







New contributor




Exposed is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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share|cite|improve this question




share|cite|improve this question






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asked Mar 11 at 19:18









ExposedExposed

1




1




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New contributor





Exposed is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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Exposed is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







  • 1




    $begingroup$
    Use formula for sum of first k terms of geometric progression where k=log_a(n)
    $endgroup$
    – Vladislav
    Mar 11 at 19:24










  • $begingroup$
    What is exactly the upper summation limit?
    $endgroup$
    – user
    Mar 11 at 19:38












  • 1




    $begingroup$
    Use formula for sum of first k terms of geometric progression where k=log_a(n)
    $endgroup$
    – Vladislav
    Mar 11 at 19:24










  • $begingroup$
    What is exactly the upper summation limit?
    $endgroup$
    – user
    Mar 11 at 19:38







1




1




$begingroup$
Use formula for sum of first k terms of geometric progression where k=log_a(n)
$endgroup$
– Vladislav
Mar 11 at 19:24




$begingroup$
Use formula for sum of first k terms of geometric progression where k=log_a(n)
$endgroup$
– Vladislav
Mar 11 at 19:24












$begingroup$
What is exactly the upper summation limit?
$endgroup$
– user
Mar 11 at 19:38




$begingroup$
What is exactly the upper summation limit?
$endgroup$
– user
Mar 11 at 19:38










1 Answer
1






active

oldest

votes


















1












$begingroup$

The formula you provided is accurate only when $log_an$ is an integer. So, to solve it by induction, you will need to prove that if the formula is true for $n$, it must also be true for $an$. For base case just using $n=1$ works.



Proof of Inductive Step :
$$displaystylesum^log_an_i=1a^i = dfraca(n-1)n-1 Rightarrow sum^log_an_i=1a^i + a^log_aan= dfraca(n-1)n-1 + an =
dfraca(n-1)+a^2n - ann-1 = dfraca(an-1)n-1 = sum^log_an+1_i=1a^i$$






share|cite|improve this answer








New contributor




Siam Habib is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






$endgroup$












  • $begingroup$
    you really helped me, thank you!
    $endgroup$
    – Exposed
    yesterday










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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









1












$begingroup$

The formula you provided is accurate only when $log_an$ is an integer. So, to solve it by induction, you will need to prove that if the formula is true for $n$, it must also be true for $an$. For base case just using $n=1$ works.



Proof of Inductive Step :
$$displaystylesum^log_an_i=1a^i = dfraca(n-1)n-1 Rightarrow sum^log_an_i=1a^i + a^log_aan= dfraca(n-1)n-1 + an =
dfraca(n-1)+a^2n - ann-1 = dfraca(an-1)n-1 = sum^log_an+1_i=1a^i$$






share|cite|improve this answer








New contributor




Siam Habib is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






$endgroup$












  • $begingroup$
    you really helped me, thank you!
    $endgroup$
    – Exposed
    yesterday















1












$begingroup$

The formula you provided is accurate only when $log_an$ is an integer. So, to solve it by induction, you will need to prove that if the formula is true for $n$, it must also be true for $an$. For base case just using $n=1$ works.



Proof of Inductive Step :
$$displaystylesum^log_an_i=1a^i = dfraca(n-1)n-1 Rightarrow sum^log_an_i=1a^i + a^log_aan= dfraca(n-1)n-1 + an =
dfraca(n-1)+a^2n - ann-1 = dfraca(an-1)n-1 = sum^log_an+1_i=1a^i$$






share|cite|improve this answer








New contributor




Siam Habib is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






$endgroup$












  • $begingroup$
    you really helped me, thank you!
    $endgroup$
    – Exposed
    yesterday













1












1








1





$begingroup$

The formula you provided is accurate only when $log_an$ is an integer. So, to solve it by induction, you will need to prove that if the formula is true for $n$, it must also be true for $an$. For base case just using $n=1$ works.



Proof of Inductive Step :
$$displaystylesum^log_an_i=1a^i = dfraca(n-1)n-1 Rightarrow sum^log_an_i=1a^i + a^log_aan= dfraca(n-1)n-1 + an =
dfraca(n-1)+a^2n - ann-1 = dfraca(an-1)n-1 = sum^log_an+1_i=1a^i$$






share|cite|improve this answer








New contributor




Siam Habib is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






$endgroup$



The formula you provided is accurate only when $log_an$ is an integer. So, to solve it by induction, you will need to prove that if the formula is true for $n$, it must also be true for $an$. For base case just using $n=1$ works.



Proof of Inductive Step :
$$displaystylesum^log_an_i=1a^i = dfraca(n-1)n-1 Rightarrow sum^log_an_i=1a^i + a^log_aan= dfraca(n-1)n-1 + an =
dfraca(n-1)+a^2n - ann-1 = dfraca(an-1)n-1 = sum^log_an+1_i=1a^i$$







share|cite|improve this answer








New contributor




Siam Habib is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|cite|improve this answer



share|cite|improve this answer






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Check out our Code of Conduct.









answered Mar 11 at 19:34









Siam HabibSiam Habib

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  • $begingroup$
    you really helped me, thank you!
    $endgroup$
    – Exposed
    yesterday
















  • $begingroup$
    you really helped me, thank you!
    $endgroup$
    – Exposed
    yesterday















$begingroup$
you really helped me, thank you!
$endgroup$
– Exposed
yesterday




$begingroup$
you really helped me, thank you!
$endgroup$
– Exposed
yesterday










Exposed is a new contributor. Be nice, and check out our Code of Conduct.









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