Ta có : `x^8 = y^2` `(1)`
Mà : `x=y` `(2)`
Thay `(2)` vào `(1)`, ta có :
`x^8=x^2`
`⇒x^8-x^2=0`
`⇒x^2(x^6-1)=0`
\(⇒\left[ \begin{array}{l}x^2=0\\x^6-1=0\end{array} \right.⇒\left[ \begin{array}{l}x=0\\x^6=1\end{array} \right.⇒\left[ \begin{array}{l}x=0\\x=±1\end{array} \right.\)
Vậy `x∈{0;±1}`