本帖最后由 王守恩 于 2023-3-5 08:48 编辑
尊敬的Treenewbee!请教一个问题。
\(题目:若x,y,d为正整数,\ \ x^2-dy^2=1, \ \ 则d=1, 4, 9, 16, 25, 36,.....无解(答案有问题)。\)
Select[Union@Flatten@Table[(y^2-1)/x^2,{x,1,50},{y,2,Sqrt[50x^2+1]}],IntegerQ[#]&]
{2, 3, 5, 6, 7, 8, 10, 11, 12, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 26,
27, 28, 30, 32, 33, 34, 35, 37, 38, 39, 40, 42, 44, 45, 47, 48, 50}
问:x 如何取值? |