`(x - 1)^4 - 16 = 0`
`⇒ (x - 1)^4 = 16`
`⇒` \(\left[ \begin{array}{l}(x - 1)^4=2^4\\(x-1)^4 = (-2)^4\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x - 1=2\\x-1 = -2\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x = 3\\x = -1\end{array} \right.\)