Đáp án:
Giải thích các bước giải:
a) x^3 - 3x^2 - 4x + 12
=(x^3 - 3x^2 )- (4x + 12)
=(x^3 - 3x^2 )+ (4x - 12)
=x^2 (x-3) + 4 (x-3)
=(x^2 +4) * ( x-3)
b) 2x^2 - 2y^2 - 6x - 6y
=( 2x^2 - 2y^2 ) - ( 6x - 6y )
= 2 ( x^2 - y^2 ) - 6 ( x - y )
=2 (x +y )*( x - y ) - 6 ( x - y )
=[ 2 (x +y ) - 6 ] * ( x - y )
c) x^3 + 3x^2 - 3x - 1
=(x^3 - 1 ) + (3x^2 - 3x )
=( x - 1 ) * ( x^2 + x +1 ) + 3x ( x - 1 )
=( x - 1 ) * [ ( x^2 + x +1 ) + 3x ]
d) x^4 - 5x^2 - 4
=( x^2 )^2 - 2 * x^2 * 2 - 2^2 - 5x^2 + 2 * x^2 * 2
=[( x^2 )^2 - 2 * x^2 * 2 - 2^2 ] - 5x^2 + 2 * x^2 * 2
= - [( x^2 )^2 + 4x^2 + 2^2 ] - 5x^2 + 4x^2
= - ( x^2 + 2 )^2 - 5x^2 + 4x^2
= - ( x^2 + 2 )^2 - x^2
= [ - ( x^2 + 2 ) + x ] * [ - ( x^2 + 2 ) - x ]