$$\\(x^3-3x^2)-(2x-6)=0\\
x^3-3x^2-2x+6=0$$
Now use remainder theorem to find a root
$$\\let\\
f(x)=x^3-3x^2-2x+6\\
f(\pm1)=\pm1-3\mp2+6\;\;=\;\;3\pm1\mp2\;\;\rightarrow\;\;2\ne0\;\;or\;\;4\ne 0\\
f(3)=27-27-6+6=0\qquad therefore\;\;x=3 \;\;$is a root$$$
(this has been edited a little)
I used polynomial division to determine that
$$\\(x^3-3x^2-2x+6)\div(x-3)=(x^2-2)\\\\
so\\\\
x^3-3x^2-2x+6=0\\\\
(x-3)(x-\sqrt2)(x+\sqrt2)=0\\\\
x=3\quad or\quad x=\sqrt2\quad or \quad x=-\sqrt2$$
.