Question

Giải phương trình:

\(\sqrt{x^2-9}-\sqrt{x^2-6x+9}=0\)

Answer 1

\(\sqrt{x^2-9}-\sqrt{x^2-6x+9}=0\Leftrightarrow\sqrt{x^2-9}=\sqrt{x^2-6x+9}\Leftrightarrow x^2-9=x^2-6x+9\Leftrightarrow-9=-6x+9\Leftrightarrow x=3\)

Answer 2

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

\(=\sqrt{x^2-3^2}-\sqrt{x^2-2\cdot3x+3^2}\)

\(=x-3-\sqrt{\left(x-3\right)^2}\)

\(=x-3-x+3\)

\(=0\)