proofverification of $lim_nrightarrowinftysqrt[n]n+s=1$ where $sge 0$ and request for an easier proof The 2019 Stack Overflow Developer Survey Results Are InProof that $lim_nrightarrow infty sqrt[n]n=1$Find $lim_n rightarrow inftysqrtn(A_n+1 − A_n)$ where $A_n = frac1n(a_1 + a_2 + cdots + a_n)$troubles proving $lim_nrightarrowinftysqrt[n]n=1$How to prove $lim_n to inftya_n=1 rightarrow lim_n to inftysqrt[n] a_n=1$find $lim_n rightarrow inftysqrtn(A_n+1 − A_n)$Prove $lim_nrightarrowinfty(a_n + b_n) = a + b$ if $lim_nrightarrowinftya_n=a$ and $lim_nrightarrowinftyb_n=b$When does equality for $x_n < y_n Rightarrow lim_n rightarrow infty x_n leq lim_n rightarrow infty y_n$ hold?If $lim_n rightarrow infty a_n = L > 0$. Prove. $lim_n rightarrow infty sqrta_n = sqrtL$ convergesShow that $limlimits_nrightarrowinfty(nb^n)=0$ for $0<b<1$Find the limit $lim_ntoinftyfracx_n + x_n^2 + cdots + x_n^k - kx_n - 1$ given $x_n ne 1$ and $lim x_n = 1$
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proofverification of $lim_nrightarrowinftysqrt[n]n+s=1$ where $sge 0$ and request for an easier proof
The 2019 Stack Overflow Developer Survey Results Are InProof that $lim_nrightarrow infty sqrt[n]n=1$Find $lim_n rightarrow inftysqrtn(A_n+1 − A_n)$ where $A_n = frac1n(a_1 + a_2 + cdots + a_n)$troubles proving $lim_nrightarrowinftysqrt[n]n=1$How to prove $lim_n to inftya_n=1 rightarrow lim_n to inftysqrt[n] a_n=1$find $lim_n rightarrow inftysqrtn(A_n+1 − A_n)$Prove $lim_nrightarrowinfty(a_n + b_n) = a + b$ if $lim_nrightarrowinftya_n=a$ and $lim_nrightarrowinftyb_n=b$When does equality for $x_n < y_n Rightarrow lim_n rightarrow infty x_n leq lim_n rightarrow infty y_n$ hold?If $lim_n rightarrow infty a_n = L > 0$. Prove. $lim_n rightarrow infty sqrta_n = sqrtL$ convergesShow that $limlimits_nrightarrowinfty(nb^n)=0$ for $0<b<1$Find the limit $lim_ntoinftyfracx_n + x_n^2 + cdots + x_n^k - kx_n - 1$ given $x_n ne 1$ and $lim x_n = 1$
$begingroup$
I have basically copied the original proof that $lim_nrightarrowinftysqrt[n]n=1$ and I hope that there are no mistakes:
$x_n=sqrt[n]n+s-1geq0$
$n+s=(x_n+1)^ngeq1+binomn2x_n^2=1+fracn(n-1)2x_n^2$
Therefore $x_nleqsqrtfrac2(n+s-1)n(n-1)$
And therefore $0leqsqrt[n]n+s-1=x_nleq sqrtfrac2(n+s-1)n(n-1)$
From now on I have stoppped to copy the original proof
$lim$ stands for $lim_nrightarrow infty$
And because $limfrac2(n-1)2(n-1)+2s=lim 1-frac2s2(n-1)+2s=1$ And the rule if $lim a_n=a>0$ then $lim sqrt[k]a_n=sqrt[k]a$
I can say (I am not sure if I am really allowed to do that, some verification would be appreciated)
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2(n+s-1)n(n-1)$$
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2(n+s-1)n(n-1)cdot 1$$
This is the step where I am asking for verification
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2(n-1)+2sn(n-1)cdot sqrtfrac2(n-1)2(n-1)+2s$$
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2n=0$$
Is the proof alright? I hope there is an easier one
real-analysis sequences-and-series proof-verification
$endgroup$
add a comment |
$begingroup$
I have basically copied the original proof that $lim_nrightarrowinftysqrt[n]n=1$ and I hope that there are no mistakes:
$x_n=sqrt[n]n+s-1geq0$
$n+s=(x_n+1)^ngeq1+binomn2x_n^2=1+fracn(n-1)2x_n^2$
Therefore $x_nleqsqrtfrac2(n+s-1)n(n-1)$
And therefore $0leqsqrt[n]n+s-1=x_nleq sqrtfrac2(n+s-1)n(n-1)$
From now on I have stoppped to copy the original proof
$lim$ stands for $lim_nrightarrow infty$
And because $limfrac2(n-1)2(n-1)+2s=lim 1-frac2s2(n-1)+2s=1$ And the rule if $lim a_n=a>0$ then $lim sqrt[k]a_n=sqrt[k]a$
I can say (I am not sure if I am really allowed to do that, some verification would be appreciated)
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2(n+s-1)n(n-1)$$
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2(n+s-1)n(n-1)cdot 1$$
This is the step where I am asking for verification
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2(n-1)+2sn(n-1)cdot sqrtfrac2(n-1)2(n-1)+2s$$
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2n=0$$
Is the proof alright? I hope there is an easier one
real-analysis sequences-and-series proof-verification
$endgroup$
1
$begingroup$
For an easier proof, notice $sqrt[n]nlesqrt[n]n+slesqrt[n]2n$ for sufficiently large $n$ and then squeeze.
$endgroup$
– Thorgott
Mar 30 at 16:21
$begingroup$
@Thorgott Why not an official answer?
$endgroup$
– Paul Frost
Mar 30 at 16:23
$begingroup$
Why the restriction on $s$?
$endgroup$
– Martín-Blas Pérez Pinilla
Mar 30 at 16:24
$begingroup$
If s is negative the root does not exist (yet) for $sqrt-1$
$endgroup$
– New2Math
Mar 30 at 16:25
$begingroup$
@New2Math, then $sge 0$ is enough. $sinBbb N$ isn't required.
$endgroup$
– Martín-Blas Pérez Pinilla
Mar 30 at 16:27
add a comment |
$begingroup$
I have basically copied the original proof that $lim_nrightarrowinftysqrt[n]n=1$ and I hope that there are no mistakes:
$x_n=sqrt[n]n+s-1geq0$
$n+s=(x_n+1)^ngeq1+binomn2x_n^2=1+fracn(n-1)2x_n^2$
Therefore $x_nleqsqrtfrac2(n+s-1)n(n-1)$
And therefore $0leqsqrt[n]n+s-1=x_nleq sqrtfrac2(n+s-1)n(n-1)$
From now on I have stoppped to copy the original proof
$lim$ stands for $lim_nrightarrow infty$
And because $limfrac2(n-1)2(n-1)+2s=lim 1-frac2s2(n-1)+2s=1$ And the rule if $lim a_n=a>0$ then $lim sqrt[k]a_n=sqrt[k]a$
I can say (I am not sure if I am really allowed to do that, some verification would be appreciated)
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2(n+s-1)n(n-1)$$
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2(n+s-1)n(n-1)cdot 1$$
This is the step where I am asking for verification
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2(n-1)+2sn(n-1)cdot sqrtfrac2(n-1)2(n-1)+2s$$
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2n=0$$
Is the proof alright? I hope there is an easier one
real-analysis sequences-and-series proof-verification
$endgroup$
I have basically copied the original proof that $lim_nrightarrowinftysqrt[n]n=1$ and I hope that there are no mistakes:
$x_n=sqrt[n]n+s-1geq0$
$n+s=(x_n+1)^ngeq1+binomn2x_n^2=1+fracn(n-1)2x_n^2$
Therefore $x_nleqsqrtfrac2(n+s-1)n(n-1)$
And therefore $0leqsqrt[n]n+s-1=x_nleq sqrtfrac2(n+s-1)n(n-1)$
From now on I have stoppped to copy the original proof
$lim$ stands for $lim_nrightarrow infty$
And because $limfrac2(n-1)2(n-1)+2s=lim 1-frac2s2(n-1)+2s=1$ And the rule if $lim a_n=a>0$ then $lim sqrt[k]a_n=sqrt[k]a$
I can say (I am not sure if I am really allowed to do that, some verification would be appreciated)
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2(n+s-1)n(n-1)$$
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2(n+s-1)n(n-1)cdot 1$$
This is the step where I am asking for verification
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2(n-1)+2sn(n-1)cdot sqrtfrac2(n-1)2(n-1)+2s$$
$$lim 0leq limsqrt[n]n+s-1=lim x_nleq lim sqrtfrac2n=0$$
Is the proof alright? I hope there is an easier one
real-analysis sequences-and-series proof-verification
real-analysis sequences-and-series proof-verification
edited Mar 30 at 16:30
New2Math
asked Mar 30 at 16:15
New2MathNew2Math
18315
18315
1
$begingroup$
For an easier proof, notice $sqrt[n]nlesqrt[n]n+slesqrt[n]2n$ for sufficiently large $n$ and then squeeze.
$endgroup$
– Thorgott
Mar 30 at 16:21
$begingroup$
@Thorgott Why not an official answer?
$endgroup$
– Paul Frost
Mar 30 at 16:23
$begingroup$
Why the restriction on $s$?
$endgroup$
– Martín-Blas Pérez Pinilla
Mar 30 at 16:24
$begingroup$
If s is negative the root does not exist (yet) for $sqrt-1$
$endgroup$
– New2Math
Mar 30 at 16:25
$begingroup$
@New2Math, then $sge 0$ is enough. $sinBbb N$ isn't required.
$endgroup$
– Martín-Blas Pérez Pinilla
Mar 30 at 16:27
add a comment |
1
$begingroup$
For an easier proof, notice $sqrt[n]nlesqrt[n]n+slesqrt[n]2n$ for sufficiently large $n$ and then squeeze.
$endgroup$
– Thorgott
Mar 30 at 16:21
$begingroup$
@Thorgott Why not an official answer?
$endgroup$
– Paul Frost
Mar 30 at 16:23
$begingroup$
Why the restriction on $s$?
$endgroup$
– Martín-Blas Pérez Pinilla
Mar 30 at 16:24
$begingroup$
If s is negative the root does not exist (yet) for $sqrt-1$
$endgroup$
– New2Math
Mar 30 at 16:25
$begingroup$
@New2Math, then $sge 0$ is enough. $sinBbb N$ isn't required.
$endgroup$
– Martín-Blas Pérez Pinilla
Mar 30 at 16:27
1
1
$begingroup$
For an easier proof, notice $sqrt[n]nlesqrt[n]n+slesqrt[n]2n$ for sufficiently large $n$ and then squeeze.
$endgroup$
– Thorgott
Mar 30 at 16:21
$begingroup$
For an easier proof, notice $sqrt[n]nlesqrt[n]n+slesqrt[n]2n$ for sufficiently large $n$ and then squeeze.
$endgroup$
– Thorgott
Mar 30 at 16:21
$begingroup$
@Thorgott Why not an official answer?
$endgroup$
– Paul Frost
Mar 30 at 16:23
$begingroup$
@Thorgott Why not an official answer?
$endgroup$
– Paul Frost
Mar 30 at 16:23
$begingroup$
Why the restriction on $s$?
$endgroup$
– Martín-Blas Pérez Pinilla
Mar 30 at 16:24
$begingroup$
Why the restriction on $s$?
$endgroup$
– Martín-Blas Pérez Pinilla
Mar 30 at 16:24
$begingroup$
If s is negative the root does not exist (yet) for $sqrt-1$
$endgroup$
– New2Math
Mar 30 at 16:25
$begingroup$
If s is negative the root does not exist (yet) for $sqrt-1$
$endgroup$
– New2Math
Mar 30 at 16:25
$begingroup$
@New2Math, then $sge 0$ is enough. $sinBbb N$ isn't required.
$endgroup$
– Martín-Blas Pérez Pinilla
Mar 30 at 16:27
$begingroup$
@New2Math, then $sge 0$ is enough. $sinBbb N$ isn't required.
$endgroup$
– Martín-Blas Pérez Pinilla
Mar 30 at 16:27
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
Easier proof:
$$lim_ntoinftylog(sqrt[n]n+s) = lim_ntoinftyfraclog(n+s)n = 0.$$
$endgroup$
add a comment |
$begingroup$
I think an easier one, goes like this:$$lim_nto inftysqrt[n]an=lim_nto inftysqrt[n]asqrt[n]n\=lim_nto infty1cdotsqrt[n]n\=lim_nto inftysqrt[n]n$$for $a>0$. Also$$lim_nto inftysqrt[n]n=lim_uto infty e^ue^-u=e^0=1$$therefore$$lim_nto inftysqrt[n]an=1$$ and hence$$1=lim_nto inftysqrt[n]nlelim_nto inftysqrt[n]n+sle lim_nto inftysqrt[n]2n=1$$which implies that$$lim_nto inftysqrt[n]n+s=1$$
$endgroup$
add a comment |
Your Answer
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Easier proof:
$$lim_ntoinftylog(sqrt[n]n+s) = lim_ntoinftyfraclog(n+s)n = 0.$$
$endgroup$
add a comment |
$begingroup$
Easier proof:
$$lim_ntoinftylog(sqrt[n]n+s) = lim_ntoinftyfraclog(n+s)n = 0.$$
$endgroup$
add a comment |
$begingroup$
Easier proof:
$$lim_ntoinftylog(sqrt[n]n+s) = lim_ntoinftyfraclog(n+s)n = 0.$$
$endgroup$
Easier proof:
$$lim_ntoinftylog(sqrt[n]n+s) = lim_ntoinftyfraclog(n+s)n = 0.$$
answered Mar 30 at 16:27
Martín-Blas Pérez PinillaMartín-Blas Pérez Pinilla
35.4k42972
35.4k42972
add a comment |
add a comment |
$begingroup$
I think an easier one, goes like this:$$lim_nto inftysqrt[n]an=lim_nto inftysqrt[n]asqrt[n]n\=lim_nto infty1cdotsqrt[n]n\=lim_nto inftysqrt[n]n$$for $a>0$. Also$$lim_nto inftysqrt[n]n=lim_uto infty e^ue^-u=e^0=1$$therefore$$lim_nto inftysqrt[n]an=1$$ and hence$$1=lim_nto inftysqrt[n]nlelim_nto inftysqrt[n]n+sle lim_nto inftysqrt[n]2n=1$$which implies that$$lim_nto inftysqrt[n]n+s=1$$
$endgroup$
add a comment |
$begingroup$
I think an easier one, goes like this:$$lim_nto inftysqrt[n]an=lim_nto inftysqrt[n]asqrt[n]n\=lim_nto infty1cdotsqrt[n]n\=lim_nto inftysqrt[n]n$$for $a>0$. Also$$lim_nto inftysqrt[n]n=lim_uto infty e^ue^-u=e^0=1$$therefore$$lim_nto inftysqrt[n]an=1$$ and hence$$1=lim_nto inftysqrt[n]nlelim_nto inftysqrt[n]n+sle lim_nto inftysqrt[n]2n=1$$which implies that$$lim_nto inftysqrt[n]n+s=1$$
$endgroup$
add a comment |
$begingroup$
I think an easier one, goes like this:$$lim_nto inftysqrt[n]an=lim_nto inftysqrt[n]asqrt[n]n\=lim_nto infty1cdotsqrt[n]n\=lim_nto inftysqrt[n]n$$for $a>0$. Also$$lim_nto inftysqrt[n]n=lim_uto infty e^ue^-u=e^0=1$$therefore$$lim_nto inftysqrt[n]an=1$$ and hence$$1=lim_nto inftysqrt[n]nlelim_nto inftysqrt[n]n+sle lim_nto inftysqrt[n]2n=1$$which implies that$$lim_nto inftysqrt[n]n+s=1$$
$endgroup$
I think an easier one, goes like this:$$lim_nto inftysqrt[n]an=lim_nto inftysqrt[n]asqrt[n]n\=lim_nto infty1cdotsqrt[n]n\=lim_nto inftysqrt[n]n$$for $a>0$. Also$$lim_nto inftysqrt[n]n=lim_uto infty e^ue^-u=e^0=1$$therefore$$lim_nto inftysqrt[n]an=1$$ and hence$$1=lim_nto inftysqrt[n]nlelim_nto inftysqrt[n]n+sle lim_nto inftysqrt[n]2n=1$$which implies that$$lim_nto inftysqrt[n]n+s=1$$
answered Apr 3 at 17:22
Mostafa AyazMostafa Ayaz
18.1k31040
18.1k31040
add a comment |
add a comment |
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$begingroup$
For an easier proof, notice $sqrt[n]nlesqrt[n]n+slesqrt[n]2n$ for sufficiently large $n$ and then squeeze.
$endgroup$
– Thorgott
Mar 30 at 16:21
$begingroup$
@Thorgott Why not an official answer?
$endgroup$
– Paul Frost
Mar 30 at 16:23
$begingroup$
Why the restriction on $s$?
$endgroup$
– Martín-Blas Pérez Pinilla
Mar 30 at 16:24
$begingroup$
If s is negative the root does not exist (yet) for $sqrt-1$
$endgroup$
– New2Math
Mar 30 at 16:25
$begingroup$
@New2Math, then $sge 0$ is enough. $sinBbb N$ isn't required.
$endgroup$
– Martín-Blas Pérez Pinilla
Mar 30 at 16:27