Phân tích đa thức thành nhân tử
a) x ( x +1 ) 2 + ( x - 5 ) - 5( x +1 )2
b) 3x2 - 12y2
c) x3 + 3x2 + 3x +1 - 27z3
d) x2 - 2xy + y2 - xz + yz
e) x2 - y2 - x - y
f) a3x - ab + b - x
g) 3x2 ( a + b + c ) + 36 xy ( a + b + c ) + 108y2( a + b + c )
h) x3 - 19x - 30
i) ab ( a - b) + bc(b-c ) + ca(c-a )
k) ( a + b + c)3 - a3 - b3 - c3
j) 4a2b2 - (a2 -+ b2 + c2 )2
HELP ME ! HELP ME ! HELP ME !
a) x ( x +1 ) 2 + ( x - 5 ) - 5( x +1 )2
=( x +1 )2.(x-5)2
=( (x +1)+(x-5)).((x +1)-(x-5))
a) x ( x +1 ) 2 + ( x - 5 ) - 5( x +1 )2
= ( x + 1 )2 ( x - 5 ) + ( x - 5 )
= ( x - 5 ) ( x2 + 2x + 1 +1 )
= ( x - 5 ) ( x2 + 2x + 2 )
b) 3x2 - 12y2
= 3 ( x2 - 4y2 )
= 3 ( x -2y ) (x + 2y )
c) x3 + 3x2 + 3x +1 - 27z3
= ( x + 1 )3 - (3z )3
= ( x + 1 - 3z ) [ ( x + 1 )2 + 3z ( x + 1 ) +9z2 ]
= ( x + 1 - 3z) [( x + 1 ) 2 + 3xz + 3z + 9z2 ]