X^n + y^n = z^n

$$\begin{gathered} {\mathrm{x}}^{\mathrm{n}}+{\mathrm{y}}^{\mathrm{n}}={\mathrm{z}}^{\mathrm{n}} \\ \mathrm{Khi} \mathrm{n}⩾3, \mathrm{Chứng} \mathrm{minh} \mathrm{rằng} : \mathrm{x},\mathrm{y},\mathrm{z} \mathrm{không} \mathrm{thể} \mathrm{là} \mathrm{số} \mathrm{nguyên} \mathrm{dương} \end{gathered}$$