phần tính nhanh !
cho mk 5 sao nha

4.a) x^2 - 4x +3
= x^2 - x -3x +3
= x(x-1) -3(x-1)
=(x-3)(x-1)
b) x^2 + x - 6
= x^2 -2x + 3x -6 
= x(x-2) + 3(x-2)
=(x+3)(x-2)
c) x^2 -5x + 6
= x^2 - 6x + x-6
=x(x-6) + (x-6)
= (x+1)(x-6)
d) x^4 - 4
= (x^2 -2 ) (x^2 +2)

4d) x^4+4 
=x^4+4x^2-4x^2+4 
=x^4+4x^2+4-4x^2 
=(x^4+4x^2+4)-4x^2 
=(x^2+2)^2-(2x)^2 
=(x^2+2+2x)(x^2+2-2x)

4 )
a)
x2 - 4x + 3 = x2 - x - 3x + 3
= x(x - 1) - 3(x - 1) = (x -1)(x - 3)
b)
x2 - x - 6 = x2 +2x - 3x - 6
= x(x + 2) - 3(x + 2)
= (x + 2)(x - 3)
Cho mk 5 sao nha

4c) x^2+5x-6 
=x^2-x+6x-6 
=x*(x-1)+6*(x-1) 
=(x-1)*(x+6)

1g)3a2-6ab+3b2-12c2

=3.(a2-2ab+b2-4c2)

=3.[(a-b)2-4c2]

=3.(a-b-2c)(a-b+2c)

1. Phân tích các đa thức sau thành nhân tử
a, 2x^2 - 2xy - 5x + 5y
= 2x(x-y) -5(x-y)
= (2x-5)(x-y)
b, 8x^2 + 4xy - 2ax - ay
= 4x(2x+y) -a(2x+y)
= (4x-a)(2x+y)
c, x^3 - 4x^2 + 4x
= x^3 - 2x^2 - 2x^2 + 4x
= x^2(x-2) -2x(x-2)
= (x^2-2x)(x-2)
d, 2xy - x^2 - y^2 + 16
= -x^2+2xy-y^2+16
= -(x^2-2xy+y^2-16)
= -((x-y)^2-4^2)
= - (x-y-4)(x-y+4)
e, x^2 - y^2 - 2yz - z^2
= -y^2-2yz-z^2+x^2
= -((y^2+2yz+z^2)-x^2)
=-(y+z)^2-x^2)
= -(y+z-x)(y+z+x)
g, 3a^2 - 6ab + 3b^2 - 12c^2
= 3(a^2-2ab+b^2-4c^2)
= 3((a-b)^2-(2c)^2)
= 3(a-b-2c)(a-b+2c)

4.a) x^2 - 4x +3
= x^2 - x -3x +3
= x(x-1) -3(x-1)
=(x-3)(x-1)

b) x^2 + x - 6
= x^2 -2x + 3x -6 
= x(x-2) + 3(x-2)
=(x+3)(x-2)

c) x^2 -5x + 6
= x^2 - 6x + x-6
=x(x-6) + (x-6)
= (x+1)(x-6)

1
a, 2x^2 - 2xy - 5x + 5y
= 2x(x-y) -5(x-y)
= (2x-5)(x-y)

B3:
a) x^3 - 1/9x = 0
=> x^3 = 1/9x
=> x^2 = 1/9
TH1: x = 0
TH2: x = -1/3
TH3: x = 1/3
b, 2x - 2y - x^2 + 2xy - y^2 = 0
=> 2(x-y) -(x-y)^2 = 0
=> (x-y))(2-(x-y)) = 0
=> (x-y)(2-x-y)= 0
=> x - y = 0
=> 2-x-y = 0
=> -x-y = 2
=> x = -1 = y
c, x( x-3 ) + x -3 = 0
=> (x+1)(x-3)=0
=> TH1: x+1=0
=> x=-1
TH2: x-3 = 0
=> x=3
d, x^2( x-3 ) + 27 - 9x = 0
=> x^2(x-3) - 9(-3+x)=0
=> (x^2-9)(x-3)=0
=> TH1:x^2 -9=0
=>x^2=9
=> x=±3
TH2: x-3=0
=> x-3

x^2-4x+3
= x^2-3x-x+3
= 3x(x-3)-(x-3)
= (3x-1)(x-3)
x^2+x-6
= x^2+3x-2x-6
= 3x(x+3)-(2x+6)
= 3x(x+3)- 2(x+3)
= (3x-2)(x+3)