Trần Nhật Quỳnh
CTV
( x - 2 )( x2 - 2x + 4 )( x + 2 )( x2 + 2x + 4 )
= [ ( x - 2 )( x2 + 2x + 4 ) ][ ( x + 2 )( x2 - 2x + 4 ) ]
= ( x3 - 8 )( x3 + 8 )
= ( x3 )2 - 82
= x6 - 64
( x-2 )( x2-2x+4)(x+2)(x2+2x+4)
=x3 - 2x2 + 4x - 2x2 - 4x - 8 + x3 + 2x + 4x + 2x2 + 4x + 8
= 2x3 + 4x2 +4x
Bài làm :
Ta có :
( x - 2 )( x2 - 2x + 4 )( x + 2 )( x2 + 2x + 4 )
= [ ( x - 2 )( x2 + 2x + 4 ) ] . [ ( x + 2 )( x2 - 2x + 4 ) ]
= ( x3 - 8 )( x3 + 8 )
= ( x3 )2 - 82
= x6 - 64