Đáp án:
\(\left[ \begin{array}{l}x=4\\x=-2\end{array} \right.\)
Giải thích các bước giải:
` (x-1)^4 = 81`
`=>`\(\left[ \begin{array}{l}(x-1)^4=3^4\\(x-1)^4=(-3)^4\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x-1=3\\x-1=-3\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x=3+1\\x=-3+1\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x=4\\x=-2\end{array} \right.\)
`text{Vậy x∈{4;-2}}`
