Question

tìm x biết:
a) x^2-2x+1=25

Answer 1

`x^2-2x+1=25`

`<=>(x-1)^2=25=5^2`

- TH1: `x-1=5<=>x=6`

- TH2: `x-1=-5<=>x=-4`

Vậy `S={6;-4}`

Answer 2

\(x^2-2x+1=25\)

\(\Leftrightarrow x^2-2.1.x+1^2=5^2\)

\(\Leftrightarrow\left(x-1\right)^2=5^2\)

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

\(\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-4\end{matrix}\right.\)

Vậy \(S=\left\{6;-4\right\}\)