2017*x^2 + 2018 = y^2
-> 2016*x^2 + x^2 + 2018 =y^2
->2016*x^2 + 2018 = y^2 -x^2
->2016*x^2 + 2018 = (y+x)*(y-x) (1)
Từ (1) ->(y+x)*(y-x)là số chẵn.
Có y+x+y-x = 2y chẵn -> y+x ; y-x cùng chẵn => (y+x)*(y-x) chia hết cho 4.
Mà 2016*x^2 + 2018 không chia hết cho 4.
Vậy không có số nguyên x;y nào thoả mãn yêu cầu bài ra.
Cho truoc diem a va duong thang d di qua diem a ve 2018 duong thang phan biet . goi x la so duong thang vuong goc voi d, y la so duong thang khong vuong goc void trong 2018 duong thang da cho..
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