a.
$xy-z+y-xz=(xy-xz)+(y-z)=x(y-z)+(y-z)=(y-z)(x+1)$
b.
$3x^2+5y-3xy-5x=(3x^2-3xy)-(5x-5y)$
$=3x(x-y)-5(x-y)=(x-y)(3x-5)$
c.
$3x^2-10xy+3y^2=(3x^2-9xy)-(xy-3y^2)=3x(x-3y)-y(x-3y)$
$=(x-3y)(3x-y)$
d.
$2x^2-5x+2=(2x^2-4x)-(x-2)=2x(x-2)-(x-2)=(x-2)(2x-1)$
e.
$8x^2-12xy+4y^2-2x-1=(9x^2-12xy+4y^2)-(x^2+2x+1)$
$=(3x-2y)^2-(x+1)^2=(3x-2y-x-1)(3x-2y+x+1)$
$=(2x-2y-1)(4x-2y+1)$
f.
$2xy-x^2+3y^2-4y+1=(4y^2-4y+1)-(x^2-2xy+y^2)$
$=(2y-1)^2-(x-y)^2=(2y-1-x+y)(2y-1+x-y)=(3y-x-1)(x+y-1)$
g.
$(x^2-3x+3)(x^2-3x+4)-12$
$=a(a+1)-12$ (đặt $x^2-3x+3=a$)
$=a^2+a-12=(a^2-3a)+(4a-12)=a(a-3)+4(a-3)=(a-3)(a+4)$
$=(x^2-3x)(x^2-3x+7)$
$=x(x-3)(x^2-3x+7)$
h.
$4x^4+16=4(x^4+4)=4[(x^2)^2+2^2+2.x^2.2-4x^2]$
$=4[(x^2+2)^2-(2x)^2]=4(x^2+2-2x)(x^2+2+2x)$
