1.
`P(x)-Q(x)=(4x^5+4x^3-5x^2+1)-(6x^5-x^4-3x^2-5)`
`=4x^5+4x^3-5x^2+1-6x^5+x^4+3x^2+5`
`=(4x^5-6x^5)+4x^3+(-5x^2+3x^2)+(1+5)+x^4`
`=-2x^5+4x^3-2x^2+6+x^4`
2.
a) `-x^2.(xy)^3.(x^3y^4)`
`=-x^2.x^3y^3.x^3y^4`
`=(-x^2x^3x^3)(y^3y^4)`
`=-x^8y^7`
Hệ số: -1.
Phần biến: `-x^8y^7`
b) `-3xyz.(-x^2z)(-yz)^3`
`=-3xyz.-x^2z.(-y^3)z^3`
$=-3\Big[x(-x^2)\Big]\Big[y(-y^3)\Big](zzz^3)$
`=-3(-x^3)(-y^4)z^5`
Hệ số: -3.
Phần biến: `-x^3(-y^4)z^5`