Find all couples $(x,y)$ over the positive integers such that: $7^x+x^4+47=y^2$
Problem
Source: Moroccan TST 2019 P3
Tags: number theory, Diophantine equation
23.08.2024 19:24
The only solution is x=4, y=52. Since 7=-1(mod4), 47=3(mod4), if x is odd,the LHS of equation is equal 3(mod4), impossible,since a square doesn't 3,mod 4. Then,x =2k. Observe that ,for k greater than 4, we have: (7^k)^2<7^2k+(2k)^4+47<(1+7^k)^2 => k is 1,2,3. Only k=2 satisfy. Done!
23.08.2024 21:07
Was this an Imo Tst or what, I thought for junior level
24.08.2024 08:53
Ziyadel wrote: Was this an Imo Tst or what, I thought for junior level I hope you understand the concept of countries being weak and strong, because this will make my text easier to understand. Since China is a strong country, its Team Selection Test is quite tough compared to the IMO. Further, Morocco isn't a very strong country, and therefore may have weaker TSTs to accomodate for the skill of participants. Along with this, it's possible that Morocco simply doesn't have many good problem proposals, and therefore has to use the problems. To conclude, please do not use phrases implying an easy difficulty without knowing the full circumstances of the country.
25.08.2024 00:15
I'm Moroccan and proud of that and our team is wonderful u'll see soon Making gold at Pamo Sorry if it was understood like that I just wanna of where is the Tst from And thanks for understanding
04.09.2024 15:32
AshAuktober wrote: Ziyadel wrote: Was this an Imo Tst or what, I thought for junior level I hope you understand the concept of countries being weak and strong, because this will make my text easier to understand. Since China is a strong country, its Team Selection Test is quite tough compared to the IMO. Further, Morocco isn't a very strong country, and therefore may have weaker TSTs to accomodate for the skill of participants. Along with this, it's possible that Morocco simply doesn't have many good problem proposals, and therefore has to use the problems. To conclude, please do not use phrases implying an easy difficulty without knowing the full circumstances of the country. This isn't IMO TST this is just a junior level exam in 2019 like grade 10 . Usually Moroccan TST's are from the shortlist!!!!
24.10.2024 21:56
AshAuktober wrote: Ziyadel wrote: Was this an Imo Tst or what, I thought for junior level I hope you understand the concept of countries being weak and strong, because this will make my text easier to understand. Since China is a strong country, its Team Selection Test is quite tough compared to the IMO. Further, Morocco isn't a very strong country, and therefore may have weaker TSTs to accomodate for the skill of participants. Along with this, it's possible that Morocco simply doesn't have many good problem proposals, and therefore has to use the problems. To conclude, please do not use phrases implying an easy difficulty without knowing the full circumstances of the country. This is just the 9th Grade test aka Junior Test , moroccan tst is usually imo shortlist problems. And Morocco is an improving country lately.