Question

structures or expressions unit test
in 1 - 2 sentences, explain why the following operation is a closed system under subtraction.
$(9x^{2}+17x + 13)-(2x^{2}+12x + 11)$
(2 points)
short answer rubric (2 points)
points awarded criteria
2 the answer is very clear.
the answer is fully supported by details.
there may be a few errors in grammar, usage, or mechanics. errors do not interfere with meaning.
1 the answer is somewhat clear

Explanation:

The expressions are polynomials. Subtracting polynomials results in a polynomial, staying within the set of polynomials.

Answer:

The operation is a closed - system under subtraction because subtracting two polynomials gives another polynomial, remaining in the same set of polynomials.