Anku posted an Question
September 15, 2021 • 15:40 pm 30 points
  • IIT JAM
  • Mathematics (MA)

Pls tell what mistake i am doing ...i have attached my explanation also..

pls tell what mistake i am doing ...i have attached my explanation also..

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  • Srj Best Answer

    Given function is discontinuous everywhere except single point pi/4. see the defination of function. it is cos at rational and sin on irrational. as both rational and irrational are dense. for any number one can find atleast one rational sequence and irrational sequence converging to that point. but both sequence limit are different on that function. so discontinuous at that point. so one can show discontinuous at each point other than pi/4. As cos and sin have same value at that point. We can prove it is not Riemann integrable. proof is same as non Riemann integrability of dirichlet function. if you want proof let me know I will add proof.

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    got it sir ..thanks a lot sir

  • Srj

    Given function is discontinuous everywhere except single point pi/4. see the defination of function. it is cos at rational and sin on irrational. as both rational and irrational are dense. for any number one can find atleast one rational sequence and irrational sequence converging to that point. but both sequence limit are different on that function. so discontinuous at that point. so one can show discontinuous at each point other than pi/4. As cos and sin have same value at that point. We can prove it is not Riemann integrable. proof is same as non Riemann integrability of dirichlet function. if you want proof let me know I will add proof.

  • Srj

    Given function is discontinuous everywhere except single point pi/4. see the defination of function. it is cos at rational and sin on irrational. as both rational and irrational are dense. for any number one can find atleast one rational sequence and irrational sequence converging to that point. but both sequence limit are different on that function. so discontinuous at that point. so one can show discontinuous at each point other than pi/4. As cos and sin have same value at that point. We can prove it is not Riemann integrable. proof is same as non Riemann integrability of dirichlet function. if you want proof let me know I will add proof.

  • Srj

    Given function is discontinuous everywhere except single point pi/4. see the defination of function. it is cos at rational and sin on irrational. as both rational and irrational are dense. for any number one can find atleast one rational sequence and irrational sequence converging to that point. but both sequence limit are different on that function. so discontinuous at that point. so one can show discontinuous at each point other than pi/4. As cos and sin have same value at that point. We can prove it is not Riemann integrable. proof is same as non Riemann integrability of dirichlet function. if you want proof let me know I will add proof.

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