Question

(x-1)^2-81=0

Answer 1

\(\left(x-1\right)^2=81\\ \left[{}\begin{matrix}\left(x-1\right)^2=9^2\\\left(x-1\right)^2=\left(-9\right)^2\end{matrix}\right.=>\left[{}\begin{matrix}x-1=9\\x-1=-9\end{matrix}\right.=>\left[{}\begin{matrix}x=10\\x=-8\end{matrix}\right.\)

Answer 2

=>(x-10)(x+8)=0

=>x=-8 hoặc x=10