Question

20 - 2( x - 1)² = 2

Answer 1

`20-2(x-1)^2 =2`

`=>2(x-1)^2 =18`

`=>(x-1)^2 =9`

`=>(x-1)^2 =(+- 3)^2`

`TH1:x-1=-3`

`=>x=-2`

`TH2:x-1=3`

`=>x=4`

Vậy `x in {-2;4}`

Answer 2

\(2\left(x-1\right)^2=20-2< =>2\left(x-1\right)^2=18< =>\left(x-1\right)^2=18:2< =>\left(x-1\right)^2=9< =>\left[{}\begin{matrix}x-1=3\\x-1=-3\end{matrix}\right.< =>\left[{}\begin{matrix}x=4\\x=-2\end{matrix}\right.\)