Re: [代數] 高中

[Honor1984 (奈何上天造化弄人？)]

※ 引述《QQLeopard (QQ)》之銘言：
: https://i.imgur.com/zlRJ4F8.jpg
: 請神人求解，謝謝：）

[x^2 - 4xy + 4y^2] + 2y^2 - 2x - 20y = 29

=> [x - 2y]^2 - 2x + 2y^2 - 20y = 29

=> [x - 2y - 1]^2 - 24y + 2y^2 = 30

=> [x - 2y - 1]^2 + 2[y - 6]^2 = 102

限制x, y均為正整數

(y - 6)^2 <= 51

=> 0 <= y <= 13

y = 13:

x - 27 = +-2

=> x = 29, 25

y = 5:

x - 11 = +-10

=> x = 21, 1

y = 7:

=> x - 15 = +-10

=> x = 25, 5


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