+) x40 = x2
\(\Rightarrow\) x40 - x2 = 0
\(\Rightarrow\) x2 . x38 - x2 . 1 = 0
\(\Rightarrow\) x2(x38 - 1) = 0
\(\Rightarrow\) \(\left[\begin{matrix}x^2=0\\x^{38}-1=0\end{matrix}\right.\)
\(\Rightarrow\) \(\left[\begin{matrix}x=0\\x^{38}=1\end{matrix}\right.\)
\(\Rightarrow\) \(\left[\begin{matrix}x=0\\x^{38}=1^{38}\end{matrix}\right.\)
\(\Rightarrow\) \(\left[\begin{matrix}x=0\\x=1\end{matrix}\right.\)
Vậy: x \(\in\) {0; 1}
+) x10 = 25 . x8
\(\Rightarrow\) x10 - 25 . x8 = 0
\(\Rightarrow\) x8 . x2 - 52 . x8 = 0
\(\Rightarrow\) x8(x2 - 52) = 0
\(\Rightarrow\left[\begin{matrix}x^8=0\\x^2-5^2=0\end{matrix}\right.\)
\(\Rightarrow\) \(\left[\begin{matrix}x=0\\x^2=5^2\end{matrix}\right.\)
\(\Rightarrow\left[\begin{matrix}x=0\\x=5\end{matrix}\right.\)
Vậy: x \(\in\) {0; 5}
