5x 3y^3 2z
I know it is in standard form because there are no more like terms.
Part B: Polynomials are always closed under multiplication. Unlike with addition and subtraction, both the coefficients and exponents can change. The variables and coefficients will automatically fit in a polynomial. When there are exponents in a multiplication problem, they are added, so they will also fit in a polynomial.
Or,
Refer to the photos:
hope this help :)
Geometric sequences go up due to a common ratio. Here the common ratio can be worked out by dividing a term by its previous term e.g term 2 divided by term 1.

Therefore the common ratio is 6.
Remember distributive property, but reverse it
ab-ac=a(b-c)
a is a common factor
find common factors
factor each
9x^2=3*3*x*x
6xy=2*3*x*y
common factor is 3*x or 3x
9x^2-6xy=3x(3x)-3x(2y)=3x(3x-2y)
factored form is 3x(3x-2y)
I would say the answer is B my good sir