Evaluate $limlimits_{nto infty} sqrt[n]{frac{2^n+n}{n^2+1}}$
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$$lim_{nto infty} sqrt[n]{frac{2^n+n}{n^2+1}}$$
I know that we can say that:
$$lim_{nto infty} sqrt[n]{frac{2^n+n}{n^2+1}}approx lim_{nto infty} sqrt[n]{frac{2^n}{n^2}}=lim_{nto infty} {frac{2}{sqrt[n]{n^2}}}=2$$
Is there another way?
calculus limits
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add a comment |
$begingroup$
$$lim_{nto infty} sqrt[n]{frac{2^n+n}{n^2+1}}$$
I know that we can say that:
$$lim_{nto infty} sqrt[n]{frac{2^n+n}{n^2+1}}approx lim_{nto infty} sqrt[n]{frac{2^n}{n^2}}=lim_{nto infty} {frac{2}{sqrt[n]{n^2}}}=2$$
Is there another way?
calculus limits
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1
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You can make it more rigorous with squeeze theorem:$$frac{2^n}{2n^2}<frac{2^n+n}{n^2+1}<frac{2cdot2^n}{n^2}$$There is also ratio implies root:$$lim_{ntoinfty}left|frac{a_{n+1}}{a_n}right|=lim_{ntoinfty}sqrt[n]{|a_n|}$$provided the left limit exists.
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– Simply Beautiful Art
Jan 14 at 12:05
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It's fine !!!!!!!
$endgroup$
– Felix Marin
Jan 14 at 19:01
add a comment |
$begingroup$
$$lim_{nto infty} sqrt[n]{frac{2^n+n}{n^2+1}}$$
I know that we can say that:
$$lim_{nto infty} sqrt[n]{frac{2^n+n}{n^2+1}}approx lim_{nto infty} sqrt[n]{frac{2^n}{n^2}}=lim_{nto infty} {frac{2}{sqrt[n]{n^2}}}=2$$
Is there another way?
calculus limits
$endgroup$
$$lim_{nto infty} sqrt[n]{frac{2^n+n}{n^2+1}}$$
I know that we can say that:
$$lim_{nto infty} sqrt[n]{frac{2^n+n}{n^2+1}}approx lim_{nto infty} sqrt[n]{frac{2^n}{n^2}}=lim_{nto infty} {frac{2}{sqrt[n]{n^2}}}=2$$
Is there another way?
calculus limits
calculus limits
edited Jan 14 at 22:38


amWhy
1
1
asked Jan 14 at 11:48
newherenewhere
858411
858411
1
$begingroup$
You can make it more rigorous with squeeze theorem:$$frac{2^n}{2n^2}<frac{2^n+n}{n^2+1}<frac{2cdot2^n}{n^2}$$There is also ratio implies root:$$lim_{ntoinfty}left|frac{a_{n+1}}{a_n}right|=lim_{ntoinfty}sqrt[n]{|a_n|}$$provided the left limit exists.
$endgroup$
– Simply Beautiful Art
Jan 14 at 12:05
$begingroup$
It's fine !!!!!!!
$endgroup$
– Felix Marin
Jan 14 at 19:01
add a comment |
1
$begingroup$
You can make it more rigorous with squeeze theorem:$$frac{2^n}{2n^2}<frac{2^n+n}{n^2+1}<frac{2cdot2^n}{n^2}$$There is also ratio implies root:$$lim_{ntoinfty}left|frac{a_{n+1}}{a_n}right|=lim_{ntoinfty}sqrt[n]{|a_n|}$$provided the left limit exists.
$endgroup$
– Simply Beautiful Art
Jan 14 at 12:05
$begingroup$
It's fine !!!!!!!
$endgroup$
– Felix Marin
Jan 14 at 19:01
1
1
$begingroup$
You can make it more rigorous with squeeze theorem:$$frac{2^n}{2n^2}<frac{2^n+n}{n^2+1}<frac{2cdot2^n}{n^2}$$There is also ratio implies root:$$lim_{ntoinfty}left|frac{a_{n+1}}{a_n}right|=lim_{ntoinfty}sqrt[n]{|a_n|}$$provided the left limit exists.
$endgroup$
– Simply Beautiful Art
Jan 14 at 12:05
$begingroup$
You can make it more rigorous with squeeze theorem:$$frac{2^n}{2n^2}<frac{2^n+n}{n^2+1}<frac{2cdot2^n}{n^2}$$There is also ratio implies root:$$lim_{ntoinfty}left|frac{a_{n+1}}{a_n}right|=lim_{ntoinfty}sqrt[n]{|a_n|}$$provided the left limit exists.
$endgroup$
– Simply Beautiful Art
Jan 14 at 12:05
$begingroup$
It's fine !!!!!!!
$endgroup$
– Felix Marin
Jan 14 at 19:01
$begingroup$
It's fine !!!!!!!
$endgroup$
– Felix Marin
Jan 14 at 19:01
add a comment |
2 Answers
2
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oldest
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$begingroup$
That approach is good, although $approx$ is a bit vague.
You can also use the fact that$$lim_{ntoinfty}sqrt[n]{frac{2^n+n}{n^2+1}}=lim_{ntoinfty}left(frac{2^n+n}{n^2+1}right)^frac1n=lim_{ntoinfty}expleft(frac{logleft(frac{2^n+n}{n^2+1}right)}nright).$$
$endgroup$
add a comment |
$begingroup$
By using the squeeze theorem:
It is $2^n+nleq n^22^n+2^n$ so you get that your limit is $leq2$. On the other hand, $2^n+ngeq2^n$ and it is $(n^2+1)^{1/n}to1$, hence your limits is $geq2$.
$endgroup$
add a comment |
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2 Answers
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2 Answers
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$begingroup$
That approach is good, although $approx$ is a bit vague.
You can also use the fact that$$lim_{ntoinfty}sqrt[n]{frac{2^n+n}{n^2+1}}=lim_{ntoinfty}left(frac{2^n+n}{n^2+1}right)^frac1n=lim_{ntoinfty}expleft(frac{logleft(frac{2^n+n}{n^2+1}right)}nright).$$
$endgroup$
add a comment |
$begingroup$
That approach is good, although $approx$ is a bit vague.
You can also use the fact that$$lim_{ntoinfty}sqrt[n]{frac{2^n+n}{n^2+1}}=lim_{ntoinfty}left(frac{2^n+n}{n^2+1}right)^frac1n=lim_{ntoinfty}expleft(frac{logleft(frac{2^n+n}{n^2+1}right)}nright).$$
$endgroup$
add a comment |
$begingroup$
That approach is good, although $approx$ is a bit vague.
You can also use the fact that$$lim_{ntoinfty}sqrt[n]{frac{2^n+n}{n^2+1}}=lim_{ntoinfty}left(frac{2^n+n}{n^2+1}right)^frac1n=lim_{ntoinfty}expleft(frac{logleft(frac{2^n+n}{n^2+1}right)}nright).$$
$endgroup$
That approach is good, although $approx$ is a bit vague.
You can also use the fact that$$lim_{ntoinfty}sqrt[n]{frac{2^n+n}{n^2+1}}=lim_{ntoinfty}left(frac{2^n+n}{n^2+1}right)^frac1n=lim_{ntoinfty}expleft(frac{logleft(frac{2^n+n}{n^2+1}right)}nright).$$
answered Jan 14 at 12:01


José Carlos SantosJosé Carlos Santos
161k22128232
161k22128232
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$begingroup$
By using the squeeze theorem:
It is $2^n+nleq n^22^n+2^n$ so you get that your limit is $leq2$. On the other hand, $2^n+ngeq2^n$ and it is $(n^2+1)^{1/n}to1$, hence your limits is $geq2$.
$endgroup$
add a comment |
$begingroup$
By using the squeeze theorem:
It is $2^n+nleq n^22^n+2^n$ so you get that your limit is $leq2$. On the other hand, $2^n+ngeq2^n$ and it is $(n^2+1)^{1/n}to1$, hence your limits is $geq2$.
$endgroup$
add a comment |
$begingroup$
By using the squeeze theorem:
It is $2^n+nleq n^22^n+2^n$ so you get that your limit is $leq2$. On the other hand, $2^n+ngeq2^n$ and it is $(n^2+1)^{1/n}to1$, hence your limits is $geq2$.
$endgroup$
By using the squeeze theorem:
It is $2^n+nleq n^22^n+2^n$ so you get that your limit is $leq2$. On the other hand, $2^n+ngeq2^n$ and it is $(n^2+1)^{1/n}to1$, hence your limits is $geq2$.
answered Jan 14 at 12:06


JustDroppedInJustDroppedIn
2,044420
2,044420
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$begingroup$
You can make it more rigorous with squeeze theorem:$$frac{2^n}{2n^2}<frac{2^n+n}{n^2+1}<frac{2cdot2^n}{n^2}$$There is also ratio implies root:$$lim_{ntoinfty}left|frac{a_{n+1}}{a_n}right|=lim_{ntoinfty}sqrt[n]{|a_n|}$$provided the left limit exists.
$endgroup$
– Simply Beautiful Art
Jan 14 at 12:05
$begingroup$
It's fine !!!!!!!
$endgroup$
– Felix Marin
Jan 14 at 19:01