\(\left(x+3\right)\left(x^2-3x+9\right)-\left(x+3\right)\left(x^2-2x-3\right)=0\)
\(\Leftrightarrow\left(x+3\right)\left(-2x+12\right)=0\Leftrightarrow x=-3;x=6\)
( x+3 ) . ( x mũ 2 − 3x + 9 ) − ( x + 3 ) ( x 2 − 2 x − 3 ) = 0
( x+3 ) . ( −2x + 12 ) = 0 => x = −3 hoặc x = 6