..cúuuuuuu

Giải thích các bước giải:

e.Ta có:

$x^3+27+(x+3)(x-9)$

$=x^3+3^3+(x+3)(x-9)$

$=(x+3)(x^2-3x+9)+(x+3)(x-9)$

$=(x+3)(x^2-3x+9+x-9)$

$=(x+3)(x^2-2x)$

$=(x+3)\cdot x(x-2)$

f.Ta có:

$5x^2+5y^2-x^2z+2xyz-y^2z-10xy$

$=(5x^2-10xy+5y^2)-(x^2z-2xyz+y^2z)$

$=5(x^2-2xy+y^2)-z(x^2-2xy+y^2)$

$=(5-z)(x^2-2xy+y^2)$

$=(5-z)(x-y)^2$