Question

(x - 2)^4 = 81

Answer 1

`#3107.101107`

`(x - 2)^4 = 81`

`=> (x - 2)^4 = (+-3)^4`

`=>`\(\left[{}\begin{matrix}x-2=3\\x-2=-3\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=3+2\\x=-3+2\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=5\\x=-1\end{matrix}\right.\)

Vậy, `x \in {-1; 5}.`

Answer 2

$(x-2)^4=81$

\(\Rightarrow (x-2)^4=(\pm 3)^4\)

\(\Rightarrow\left[{}\begin{matrix}x-2=3\\x-2=-3\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=5\\x=-1\end{matrix}\right.\)

Vậy $x\in \{5;-1\}$.