Question

rút gọn x - 3 - căn x^2 -6x +9

Answer 1

\(x-3-\sqrt{x^2-6x+9}\left(1\right)=x-3-\sqrt{\left(x-3\right)^2}=x-3-\left|x-3\right|\)

TH1: \(x< 3\)

\(\left(1\right)=x-3+x-3=2x-6\)

TH2: \(x\ge3\)

\(\left(1\right)=x-3-x+3=0\)

 

Answer 2

\(x-3-\sqrt{x^2-6x+9}\)

\(=x-3-\left|x-3\right|\)

\(=\left[{}\begin{matrix}x-3-x+3=0\left(x\ge3\right)\\x-3+x-3=2x-6\left(x< 3\right)\end{matrix}\right.\)