a) 2x^3-x^2+x b) x^2-y^2-x+y c) x^2 – 2x +1- x +1 d) 3xyz-9yz Giúp mình với

a, $2x^3-x^2+x$

$=x(2x^2-x+1)$

b, $x^2-y^2-x+y$

$=(x^2-y^2)-(x-y)$

$=(x-y)(x+y)-(x-y)$

$=(x-y)(x+y-1)$

c, $x^2-2x+1-x+1$

$=(x^2-2x+1)-(x-1)$

$=(x-1)^2-(x-1)$

$=(x-1)(x-1-1)$

$=(x-1)(x-2)$

d, $3xyz-9yz$

$=3yz(x-3)$