Câu 1 :
a) $3x^{2}$ ( $4x^{3}$ + 2x - 4 ) = $12x^{5}$ + $6x^{3}$ - $12x^{2}$
b) ( $x^{3}$ + $3x^{2}$ + x - 3 ) : ( x - 3 ) = $x^{2}$ - 1 = ( x + 1)( x - 1 )
Câu 2:
a) $2x^{2}$ + 2xy- x - y = 2x ( x + y ) - ( x + y ) = ( x + y ) ( 2x - 1 )
b)$x^{2}$ - 2x - 3 = $x^{2}$ + x - 3x - 3 = x ( x + 1 ) - 3 ( x + 1 ) = ( x + 1 ) ( x - 3 )