Is $f$ and $g$ is Riemann-integrable?












-1














let $f : [0,1] rightarrow mathbb{R}$ and $g:[0,1] rightarrow mathbb{R}$ be two function define by



$$f(x) =
begin{cases}
frac {1}{n},text{ if }x = frac{1}{n},n in mathbb{N}\
0, text{otherwise}end{cases}$$
and $$g(x) =
begin{cases}
n,text{ if } x = frac{1}{n}, n in mathbb{N} \
0, text{ otherwise}.end{cases}$$



Then choose the correct option



$a)$ both $f$ and g are Riemann-integrable



$b)$ $f$ is Riemann-integrable but $g$ is not



$c)$ $g$ is Riemann-integrable but $f$ is not



$d)$ neither $f$ nor $g$ is Riemann-integrable



i thinks option $d)$ will correct that is neither $f$ nor $g$ is Riemann-integrable because $f$ and $g$ are not continuous.



Is its True ??










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  • 2




    Is it true that Riemann integrable functions must be continuous?
    – Saucy O'Path
    Nov 20 '18 at 23:28










  • @SaucyO'Path ya i missed that
    – Messi fifa
    Nov 20 '18 at 23:35
















-1














let $f : [0,1] rightarrow mathbb{R}$ and $g:[0,1] rightarrow mathbb{R}$ be two function define by



$$f(x) =
begin{cases}
frac {1}{n},text{ if }x = frac{1}{n},n in mathbb{N}\
0, text{otherwise}end{cases}$$
and $$g(x) =
begin{cases}
n,text{ if } x = frac{1}{n}, n in mathbb{N} \
0, text{ otherwise}.end{cases}$$



Then choose the correct option



$a)$ both $f$ and g are Riemann-integrable



$b)$ $f$ is Riemann-integrable but $g$ is not



$c)$ $g$ is Riemann-integrable but $f$ is not



$d)$ neither $f$ nor $g$ is Riemann-integrable



i thinks option $d)$ will correct that is neither $f$ nor $g$ is Riemann-integrable because $f$ and $g$ are not continuous.



Is its True ??










share|cite|improve this question




















  • 2




    Is it true that Riemann integrable functions must be continuous?
    – Saucy O'Path
    Nov 20 '18 at 23:28










  • @SaucyO'Path ya i missed that
    – Messi fifa
    Nov 20 '18 at 23:35














-1












-1








-1







let $f : [0,1] rightarrow mathbb{R}$ and $g:[0,1] rightarrow mathbb{R}$ be two function define by



$$f(x) =
begin{cases}
frac {1}{n},text{ if }x = frac{1}{n},n in mathbb{N}\
0, text{otherwise}end{cases}$$
and $$g(x) =
begin{cases}
n,text{ if } x = frac{1}{n}, n in mathbb{N} \
0, text{ otherwise}.end{cases}$$



Then choose the correct option



$a)$ both $f$ and g are Riemann-integrable



$b)$ $f$ is Riemann-integrable but $g$ is not



$c)$ $g$ is Riemann-integrable but $f$ is not



$d)$ neither $f$ nor $g$ is Riemann-integrable



i thinks option $d)$ will correct that is neither $f$ nor $g$ is Riemann-integrable because $f$ and $g$ are not continuous.



Is its True ??










share|cite|improve this question















let $f : [0,1] rightarrow mathbb{R}$ and $g:[0,1] rightarrow mathbb{R}$ be two function define by



$$f(x) =
begin{cases}
frac {1}{n},text{ if }x = frac{1}{n},n in mathbb{N}\
0, text{otherwise}end{cases}$$
and $$g(x) =
begin{cases}
n,text{ if } x = frac{1}{n}, n in mathbb{N} \
0, text{ otherwise}.end{cases}$$



Then choose the correct option



$a)$ both $f$ and g are Riemann-integrable



$b)$ $f$ is Riemann-integrable but $g$ is not



$c)$ $g$ is Riemann-integrable but $f$ is not



$d)$ neither $f$ nor $g$ is Riemann-integrable



i thinks option $d)$ will correct that is neither $f$ nor $g$ is Riemann-integrable because $f$ and $g$ are not continuous.



Is its True ??







real-analysis integration riemann-integration






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edited Nov 20 '18 at 23:40









Batominovski

33.9k33292




33.9k33292










asked Nov 20 '18 at 23:26









Messi fifa

51611




51611








  • 2




    Is it true that Riemann integrable functions must be continuous?
    – Saucy O'Path
    Nov 20 '18 at 23:28










  • @SaucyO'Path ya i missed that
    – Messi fifa
    Nov 20 '18 at 23:35














  • 2




    Is it true that Riemann integrable functions must be continuous?
    – Saucy O'Path
    Nov 20 '18 at 23:28










  • @SaucyO'Path ya i missed that
    – Messi fifa
    Nov 20 '18 at 23:35








2




2




Is it true that Riemann integrable functions must be continuous?
– Saucy O'Path
Nov 20 '18 at 23:28




Is it true that Riemann integrable functions must be continuous?
– Saucy O'Path
Nov 20 '18 at 23:28












@SaucyO'Path ya i missed that
– Messi fifa
Nov 20 '18 at 23:35




@SaucyO'Path ya i missed that
– Messi fifa
Nov 20 '18 at 23:35










1 Answer
1






active

oldest

votes


















2














b) is the correct answer. $g$ is not even a bounded function so it is not a Riemann integrable. $f$ is Riemann integrable because it is bounded and continuous almost everywhere.






share|cite|improve this answer





















  • one more doubts @Kavi sir $g(x)$ has countable point of discontinuity i mean it can be reimann integrable ??
    – Messi fifa
    Nov 20 '18 at 23:35






  • 1




    Yes, any bounded function with only countable number of discontinuities is Riemann integrable.
    – Kavi Rama Murthy
    Nov 20 '18 at 23:36










  • okkss thanks u sir i gots its
    – Messi fifa
    Nov 20 '18 at 23:37











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1 Answer
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active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

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active

oldest

votes









2














b) is the correct answer. $g$ is not even a bounded function so it is not a Riemann integrable. $f$ is Riemann integrable because it is bounded and continuous almost everywhere.






share|cite|improve this answer





















  • one more doubts @Kavi sir $g(x)$ has countable point of discontinuity i mean it can be reimann integrable ??
    – Messi fifa
    Nov 20 '18 at 23:35






  • 1




    Yes, any bounded function with only countable number of discontinuities is Riemann integrable.
    – Kavi Rama Murthy
    Nov 20 '18 at 23:36










  • okkss thanks u sir i gots its
    – Messi fifa
    Nov 20 '18 at 23:37
















2














b) is the correct answer. $g$ is not even a bounded function so it is not a Riemann integrable. $f$ is Riemann integrable because it is bounded and continuous almost everywhere.






share|cite|improve this answer





















  • one more doubts @Kavi sir $g(x)$ has countable point of discontinuity i mean it can be reimann integrable ??
    – Messi fifa
    Nov 20 '18 at 23:35






  • 1




    Yes, any bounded function with only countable number of discontinuities is Riemann integrable.
    – Kavi Rama Murthy
    Nov 20 '18 at 23:36










  • okkss thanks u sir i gots its
    – Messi fifa
    Nov 20 '18 at 23:37














2












2








2






b) is the correct answer. $g$ is not even a bounded function so it is not a Riemann integrable. $f$ is Riemann integrable because it is bounded and continuous almost everywhere.






share|cite|improve this answer












b) is the correct answer. $g$ is not even a bounded function so it is not a Riemann integrable. $f$ is Riemann integrable because it is bounded and continuous almost everywhere.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Nov 20 '18 at 23:29









Kavi Rama Murthy

51k31854




51k31854












  • one more doubts @Kavi sir $g(x)$ has countable point of discontinuity i mean it can be reimann integrable ??
    – Messi fifa
    Nov 20 '18 at 23:35






  • 1




    Yes, any bounded function with only countable number of discontinuities is Riemann integrable.
    – Kavi Rama Murthy
    Nov 20 '18 at 23:36










  • okkss thanks u sir i gots its
    – Messi fifa
    Nov 20 '18 at 23:37


















  • one more doubts @Kavi sir $g(x)$ has countable point of discontinuity i mean it can be reimann integrable ??
    – Messi fifa
    Nov 20 '18 at 23:35






  • 1




    Yes, any bounded function with only countable number of discontinuities is Riemann integrable.
    – Kavi Rama Murthy
    Nov 20 '18 at 23:36










  • okkss thanks u sir i gots its
    – Messi fifa
    Nov 20 '18 at 23:37
















one more doubts @Kavi sir $g(x)$ has countable point of discontinuity i mean it can be reimann integrable ??
– Messi fifa
Nov 20 '18 at 23:35




one more doubts @Kavi sir $g(x)$ has countable point of discontinuity i mean it can be reimann integrable ??
– Messi fifa
Nov 20 '18 at 23:35




1




1




Yes, any bounded function with only countable number of discontinuities is Riemann integrable.
– Kavi Rama Murthy
Nov 20 '18 at 23:36




Yes, any bounded function with only countable number of discontinuities is Riemann integrable.
– Kavi Rama Murthy
Nov 20 '18 at 23:36












okkss thanks u sir i gots its
– Messi fifa
Nov 20 '18 at 23:37




okkss thanks u sir i gots its
– Messi fifa
Nov 20 '18 at 23:37


















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