Tìm cặp số nguyên (x;y) biết 2xy-y+4x=13

1 bình luận về “Tìm cặp số nguyên (x;y) biết 2xy-y+4x=13”

1. 2xy – y + 4x = 13

   y(2x-1) + 2x + 2x = 13

   y(2x-1) + (2x-1) + (2x-1) = 13 – 1 – 1 = 11

   (y+2)(2x-1) = 11

   Có : 11 = 1.11 = (-1)(-11)

   Nên ta có :

   \begin{array}{|c|c|c|}\hline \text{y+2}&\text{1}&\text{11}&\text{-1}&\text{-11}\\\hline \text{2x-1}&\text{11}&\text{1}&\text{-11}&\text{-1}\\\hline \text{y}&\text{-1}&\text{9}&\text{-3}&\text{-13}\\\hline \text{x}&\text{6}&\text{1}&\text{-5}&\text{0}\\\hline\end{array}

    

   Trả lời