Tìm x,y nguyên dương thỏa mãn
$y^{4}+4xy(x^{2}+y^{2})+6x^{2}y^{2}=4x^{3}+6x^{2}+3x+2$
$y^{4}+4xy(x^{2}+y^{2})+6x^{2}y^{2}=4x^{3}+6x^{2}+3x+2$
Started By Just4Mgl, 23-05-2021 - 17:14
#1
Posted 23-05-2021 - 17:14
#2
Posted 23-05-2021 - 18:14
Tìm x,y nguyên dương thỏa mãn
$y^{4}+4xy(x^{2}+y^{2})+6x^{2}y^{2}=4x^{3}+6x^{2}+3x+2$
$\large \Leftrightarrow (x^{2}+y^{2})^{2}+4xy(x^{2}+y^{2})+4x^{2}y^{2}=x^{4}+4x^{3}+6x^{2}+3x+2 \Rightarrow x^{4}+4x^{3}+6x^{2}+3x+2$ là số chính phương.
Kẹp $\large (x^{2}+2x)^{2}< x^{4}+4x^{3}+6x^{2}+3x+2\leq (x^{2}+2x+1)^{2}$
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