Number Theory: Divisibilty

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Q: Prove that if a and b are positive integers satisfying (a,b)=[a,b}, then a=b.



My approach (with ans):
(a,b) means gcd, and I let g=(a,b)
since g is the gcd,
then I get these two: g|a and g|b, while g


Next is [a,b], the lcm of a and b, and I let it be h.
then I get another two of these: a|h and b|h while a


Combine the inequalities together will get:
g


Since the question provides that g=h,
so h


Is the a correct explanation? As I hope to get full credits, I hope I can present my answers as detail as possible (without any faults). Thank you.










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  • 1




    Combine the inequalities Which inequalities? There is no inequality in the posted question. However, it would be enough to argue that $,(a,b) le a le [a,b],$.
    – dxiv
    Sep 7 at 7:16











  • Oh, i may miss typing (a,b)≤a≤[a,b]. Thank you very much.
    – Jason Ng
    Sep 7 at 7:26














up vote
0
down vote

favorite












Q: Prove that if a and b are positive integers satisfying (a,b)=[a,b}, then a=b.



My approach (with ans):
(a,b) means gcd, and I let g=(a,b)
since g is the gcd,
then I get these two: g|a and g|b, while g


Next is [a,b], the lcm of a and b, and I let it be h.
then I get another two of these: a|h and b|h while a


Combine the inequalities together will get:
g


Since the question provides that g=h,
so h


Is the a correct explanation? As I hope to get full credits, I hope I can present my answers as detail as possible (without any faults). Thank you.










share|cite|improve this question

















  • 1




    Combine the inequalities Which inequalities? There is no inequality in the posted question. However, it would be enough to argue that $,(a,b) le a le [a,b],$.
    – dxiv
    Sep 7 at 7:16











  • Oh, i may miss typing (a,b)≤a≤[a,b]. Thank you very much.
    – Jason Ng
    Sep 7 at 7:26












up vote
0
down vote

favorite









up vote
0
down vote

favorite











Q: Prove that if a and b are positive integers satisfying (a,b)=[a,b}, then a=b.



My approach (with ans):
(a,b) means gcd, and I let g=(a,b)
since g is the gcd,
then I get these two: g|a and g|b, while g


Next is [a,b], the lcm of a and b, and I let it be h.
then I get another two of these: a|h and b|h while a


Combine the inequalities together will get:
g


Since the question provides that g=h,
so h


Is the a correct explanation? As I hope to get full credits, I hope I can present my answers as detail as possible (without any faults). Thank you.










share|cite|improve this question













Q: Prove that if a and b are positive integers satisfying (a,b)=[a,b}, then a=b.



My approach (with ans):
(a,b) means gcd, and I let g=(a,b)
since g is the gcd,
then I get these two: g|a and g|b, while g


Next is [a,b], the lcm of a and b, and I let it be h.
then I get another two of these: a|h and b|h while a


Combine the inequalities together will get:
g


Since the question provides that g=h,
so h


Is the a correct explanation? As I hope to get full credits, I hope I can present my answers as detail as possible (without any faults). Thank you.







number-theory divisibility greatest-common-divisor least-common-multiple






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asked Sep 7 at 7:12









Jason Ng

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  • 1




    Combine the inequalities Which inequalities? There is no inequality in the posted question. However, it would be enough to argue that $,(a,b) le a le [a,b],$.
    – dxiv
    Sep 7 at 7:16











  • Oh, i may miss typing (a,b)≤a≤[a,b]. Thank you very much.
    – Jason Ng
    Sep 7 at 7:26












  • 1




    Combine the inequalities Which inequalities? There is no inequality in the posted question. However, it would be enough to argue that $,(a,b) le a le [a,b],$.
    – dxiv
    Sep 7 at 7:16











  • Oh, i may miss typing (a,b)≤a≤[a,b]. Thank you very much.
    – Jason Ng
    Sep 7 at 7:26







1




1




Combine the inequalities Which inequalities? There is no inequality in the posted question. However, it would be enough to argue that $,(a,b) le a le [a,b],$.
– dxiv
Sep 7 at 7:16





Combine the inequalities Which inequalities? There is no inequality in the posted question. However, it would be enough to argue that $,(a,b) le a le [a,b],$.
– dxiv
Sep 7 at 7:16













Oh, i may miss typing (a,b)≤a≤[a,b]. Thank you very much.
– Jason Ng
Sep 7 at 7:26




Oh, i may miss typing (a,b)≤a≤[a,b]. Thank you very much.
– Jason Ng
Sep 7 at 7:26















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