\(a.6x^3y^2.\left(2-x\right)+9x^2y^2.\left(x-2\right)\\ =6x^3y^2.\left(2-x\right)-9x^2y^2.\left(2-x\right)\\ =3x^2y^2\left(2-x\right)\left(2x-3\right)\)
Lời giải:
a.
$=6x^3y^2(2-x)-9x^2y^2(2-x)$
$=(2-x)(6x^3y^2-9x^2y^2)$
$=(2-x).3x^2y^2(2x-3)=3x^2y^2(2-x)(2x-3)$
b.
$=(x^2-y^2)-(4x-4y)=(x-y)(x+y)-4(x-y)$
$=(x-y)(x+y-4)$
c.
$81x^2-(9y^2-6yz+z^2)$
$=(9x)^2-(3y-z)^2=(9x-3y+z)(9x+3y-z)$