`4^( 2x + 1 ) = 64`
`⇔ 4^( 2x + 1 ) = 4^3`
`⇔ 2x + 1 = 3`
`⇔ 2x = 3 - 1`
`⇔ 2x = 2`
`⇔ x = 2 : 2`
`⇔ x = 1`
Vậy `, x = 1 .`
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`x^17 = x`
`⇔ x^17 - x = 0`
`⇔ x . x^16 - x = 0`
`⇔ x . ( x^16 - 1 ) = 0`
`⇔` $\left[\begin{matrix}x = 0\\x^{16} - 1 = 0\end{matrix}\right.$
`⇔` $\left[\begin{matrix}x = 0\\x^{16} = 1\end{matrix}\right.$
`⇔` $\left[\begin{matrix}x = 0\\x = 1\\ x = - 1\end{matrix}\right.$
Vậy `, x ∈ { 0 ; 1 ; - 1 } .`
