Question

x^2 -2.(x+3)=x-6

Answer 1

\(x^2-2\left(x+3\right)=x-6\\ \Rightarrow x^2-2x-6=x-6\\ \Rightarrow x^2-2x-6-x+6=0\\ \Rightarrow x^2-3x=0\\ \Rightarrow x\left(x-3\right)=0\)

TH1: x = 0

TH2: x - 3 = 0 => x = 3 

Vậy: ... 

Answer 2

\(x^2-2.(x+3)=x-6\\\Leftrightarrow x^2-2x-6=x-6\\\Leftrightarrow x^2-3x=0\\\Leftrightarrow x (x-3)=0\\\Leftrightarrow \left[\begin{array}{} x=0\\ x-3=0 \end{array} \right.\Leftrightarrow \left[\begin{array}{} x=0\\ x=3 \end{array} \right.\)

Vậy: ...