Remainder Estimate for Integral test












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$begingroup$


I have the following question, it is a fill in the blank type question, however when I submit my answer, the system which verifies it say it is incorrect. I believe I am right, so I was hoping for someone to show me where I am going wrong.



Here is the question.




Accuracy to within 0.0005 means that we have to find the value of $n$ such that $R_n le$ ____.



Since $R_n le int_{n}^infty frac{4dx}{x^3} = lim_{ttoinfty} int_{n}^t frac{4dx}{x^3} = $_____.



We want ____ $le $ _____.



Solving this inequality we get $ n ge$ ____ $approx$ ______.




Here is my solution



Accuracy to within 0.0005 means that we have to find the value of $n$ such that $R_n le$ 0.0005.



Since $R_n le int_{n}^infty frac{4dx}{x^3} = lim_{ttoinfty} int_{n}^t frac{4dx}{x^3} = frac{4}{2n^2}$.



We want $frac{4}{2n^2}le 0.0005$



Solving this inequality we get $ n ge sqrt{frac{4}{2cdot0.0005}} approx$ 63.24555.



Some other notes... I am pretty convinced that all the blanks are correct except the last blank, thus I have tried 64 as another answer (however that was also flagged as incorrect).










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$endgroup$












  • $begingroup$
    The notation $R_n$ has many uses. Just what does it mean here? And the expression you put in the second blank is not simplified. The computer probably wants $dfrac{2}{n^2}$ or perhaps $2n^{-2}$.
    $endgroup$
    – Rory Daulton
    Jul 29 '15 at 0:35
















1












$begingroup$


I have the following question, it is a fill in the blank type question, however when I submit my answer, the system which verifies it say it is incorrect. I believe I am right, so I was hoping for someone to show me where I am going wrong.



Here is the question.




Accuracy to within 0.0005 means that we have to find the value of $n$ such that $R_n le$ ____.



Since $R_n le int_{n}^infty frac{4dx}{x^3} = lim_{ttoinfty} int_{n}^t frac{4dx}{x^3} = $_____.



We want ____ $le $ _____.



Solving this inequality we get $ n ge$ ____ $approx$ ______.




Here is my solution



Accuracy to within 0.0005 means that we have to find the value of $n$ such that $R_n le$ 0.0005.



Since $R_n le int_{n}^infty frac{4dx}{x^3} = lim_{ttoinfty} int_{n}^t frac{4dx}{x^3} = frac{4}{2n^2}$.



We want $frac{4}{2n^2}le 0.0005$



Solving this inequality we get $ n ge sqrt{frac{4}{2cdot0.0005}} approx$ 63.24555.



Some other notes... I am pretty convinced that all the blanks are correct except the last blank, thus I have tried 64 as another answer (however that was also flagged as incorrect).










share|cite|improve this question











$endgroup$












  • $begingroup$
    The notation $R_n$ has many uses. Just what does it mean here? And the expression you put in the second blank is not simplified. The computer probably wants $dfrac{2}{n^2}$ or perhaps $2n^{-2}$.
    $endgroup$
    – Rory Daulton
    Jul 29 '15 at 0:35














1












1








1





$begingroup$


I have the following question, it is a fill in the blank type question, however when I submit my answer, the system which verifies it say it is incorrect. I believe I am right, so I was hoping for someone to show me where I am going wrong.



Here is the question.




Accuracy to within 0.0005 means that we have to find the value of $n$ such that $R_n le$ ____.



Since $R_n le int_{n}^infty frac{4dx}{x^3} = lim_{ttoinfty} int_{n}^t frac{4dx}{x^3} = $_____.



We want ____ $le $ _____.



Solving this inequality we get $ n ge$ ____ $approx$ ______.




Here is my solution



Accuracy to within 0.0005 means that we have to find the value of $n$ such that $R_n le$ 0.0005.



Since $R_n le int_{n}^infty frac{4dx}{x^3} = lim_{ttoinfty} int_{n}^t frac{4dx}{x^3} = frac{4}{2n^2}$.



We want $frac{4}{2n^2}le 0.0005$



Solving this inequality we get $ n ge sqrt{frac{4}{2cdot0.0005}} approx$ 63.24555.



Some other notes... I am pretty convinced that all the blanks are correct except the last blank, thus I have tried 64 as another answer (however that was also flagged as incorrect).










share|cite|improve this question











$endgroup$




I have the following question, it is a fill in the blank type question, however when I submit my answer, the system which verifies it say it is incorrect. I believe I am right, so I was hoping for someone to show me where I am going wrong.



Here is the question.




Accuracy to within 0.0005 means that we have to find the value of $n$ such that $R_n le$ ____.



Since $R_n le int_{n}^infty frac{4dx}{x^3} = lim_{ttoinfty} int_{n}^t frac{4dx}{x^3} = $_____.



We want ____ $le $ _____.



Solving this inequality we get $ n ge$ ____ $approx$ ______.




Here is my solution



Accuracy to within 0.0005 means that we have to find the value of $n$ such that $R_n le$ 0.0005.



Since $R_n le int_{n}^infty frac{4dx}{x^3} = lim_{ttoinfty} int_{n}^t frac{4dx}{x^3} = frac{4}{2n^2}$.



We want $frac{4}{2n^2}le 0.0005$



Solving this inequality we get $ n ge sqrt{frac{4}{2cdot0.0005}} approx$ 63.24555.



Some other notes... I am pretty convinced that all the blanks are correct except the last blank, thus I have tried 64 as another answer (however that was also flagged as incorrect).







calculus sequences-and-series improper-integrals solution-verification






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edited Jul 28 '15 at 23:44







user147263

















asked Jul 28 '15 at 23:16









darockadarocka

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112












  • $begingroup$
    The notation $R_n$ has many uses. Just what does it mean here? And the expression you put in the second blank is not simplified. The computer probably wants $dfrac{2}{n^2}$ or perhaps $2n^{-2}$.
    $endgroup$
    – Rory Daulton
    Jul 29 '15 at 0:35


















  • $begingroup$
    The notation $R_n$ has many uses. Just what does it mean here? And the expression you put in the second blank is not simplified. The computer probably wants $dfrac{2}{n^2}$ or perhaps $2n^{-2}$.
    $endgroup$
    – Rory Daulton
    Jul 29 '15 at 0:35
















$begingroup$
The notation $R_n$ has many uses. Just what does it mean here? And the expression you put in the second blank is not simplified. The computer probably wants $dfrac{2}{n^2}$ or perhaps $2n^{-2}$.
$endgroup$
– Rory Daulton
Jul 29 '15 at 0:35




$begingroup$
The notation $R_n$ has many uses. Just what does it mean here? And the expression you put in the second blank is not simplified. The computer probably wants $dfrac{2}{n^2}$ or perhaps $2n^{-2}$.
$endgroup$
– Rory Daulton
Jul 29 '15 at 0:35










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