Consider the following polynomials equations
A= 3x^2 (x-1)
B= -3x^3 + 4x^2 - 2x +1

Answer with explanation:
An expression of the form [tex]A_{0}x^n+A_{1}x^{n-1}+.............+A_{n}[/tex] is called a Polynomial,if it consist of only one variable in entire terms, and degree of each variable is non negative integer.
The given Polynomial are
[tex]A=3x^2(x-1)\\\\B= -3 x^3 + 4 x^2 - 2 x +1[/tex]
[tex]1. A +B=3x^2(x-1) + [-3 x^3 + 4 x^2 - 2 x +1]\\\\=3x^3- 3 x^2 -3x^3+4 x^2- 2 x + 1\\\\{\text{Adding and subtracting like terms}}\\\\=x^2-2 x +1\\\\2. A - B=3x^2(x-1) - [-3 x^3 + 4 x^2 - 2 x +1]\\\\=3x^3- 3 x^2 +3x^3-4 x^2+ 2 x - 1\\\\{\text{Adding and subtracting like terms}}\\\\=6 x^3-7 x^2+2 x -1\\\\3. A \times B=[3x^2(x-1)] \times [-3 x^3 + 4 x^2 - 2 x +1]\\\\=[3 x^3-3 x^2]\times [-3 x^3 + 4 x^2 - 2 x +1]\\\\3 x^3\times [-3 x^3 + 4 x^2 - 2 x +1]-3 x^2\times [-3 x^3 + 4 x^2 - 2 x +1][/tex]
[tex]=-9x ^6+12 x^5-6 x^4+3 x^3+9 x^5-12 x^4+6 x^3-3 x^2\\\\{\text{Adding and subtracting like terms and used property of exponents}}\rightarrow x^a\times x^b=x^{a+b}\\\\-9 x^6+21 x^5-18 x^4+9 x^3-3 x^2[/tex]
→→→All the three, that is
1.A +B
2. A -B
3. A× B
are Polynomials