$n^4+2n^3+2n^2+2n+1=y^2$
#1
Đã gửi 28-10-2012 - 17:28
Discovery is a child’s privilege. I mean the small child, the child who is not afraid to be wrong, to look silly, to not be serious, and to act differently from everyone else. He is also not afraid that the things he is interested in are in bad taste or turn out to be different from his expectations, from what they should be, or rather he is not afraid of what they actually are. He ignores the silent and flawless consensus that is part of the air we breathe – the consensus of all the people who are, or are reputed to be, reasonable.
Grothendieck, Récoltes et Semailles (“Crops and Seeds”).
#2
Đã gửi 28-10-2012 - 17:42
$n^4+2n^3+2n^2+2n+1=(n^2+1)(n+1)^2$Giải phương trình nghiệm nguyên $$n^4+2n^3+2n^2+2n+1=y^2$$
Để $$n^4+2n^3+2n^2+2n+1=y^2$$ thì $n^2+1$ phải là số chính phương.
Đặt $n^2+1=k^2\Leftrightarrow 1=(k-n)(k+n)\Leftrightarrow n=0$
Vậy nghiệm phương trình là $(n;y)=(0;1);(0;-1)$
P/s:Quên $0$ cũng là số chính phương.Hic!
Bài viết đã được chỉnh sửa nội dung bởi doxuantung97: 28-10-2012 - 17:46
- NguyenVietKhanh, LeHoangAnh1997 và Nguyen Viet Khanh thích
#3
Đã gửi 28-10-2012 - 17:42
$$\Leftrightarrow (n^2+1)(n+1)^2=y^2$$Giải phương trình nghiệm nguyên $$n^4+2n^3+2n^2+2n+1=y^2$$
TH1: $n+1=y=0...$
TH2: $n+1,y\ne 0\Rightarrow n^2+1$ là số chính phương ...
Kết hợp 2TH có nghiệm: $(n;y)=(-1;0);(0;1);(0;-1)$
Bài này Toàn khúc mắc chỗ nào nhỉ?
Bài viết đã được chỉnh sửa nội dung bởi minhtuyb: 28-10-2012 - 17:44
- LeHoangAnh1997 yêu thích
#4
Đã gửi 28-10-2012 - 18:56
Discovery is a child’s privilege. I mean the small child, the child who is not afraid to be wrong, to look silly, to not be serious, and to act differently from everyone else. He is also not afraid that the things he is interested in are in bad taste or turn out to be different from his expectations, from what they should be, or rather he is not afraid of what they actually are. He ignores the silent and flawless consensus that is part of the air we breathe – the consensus of all the people who are, or are reputed to be, reasonable.
Grothendieck, Récoltes et Semailles (“Crops and Seeds”).
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