In 1–2 sentences, explain why the following operation is a closed system under subtraction.

(9x^2 + 17x + 13) − (2x^2 + 12x + 11)

The operation of subtraction is a closed system because it yields a polynomial with real coefficients when subtracting two polynomials with real coefficients.

Use the Distributive Property to prove that these algebraic expressions are equivalent. Explain your answer in one sentence for each expression and show your work.

Expression 1: (x − 5) * (x + 3)

Expression 2: 2x^2 − x2 − 2x − 20 + 5

Expression 1: (x - 5) * (x + 3) is equivalent to Expression 2: 2x^2 - x^2 - 2x - 20 + 5, because when using the Distributive Property, the first term in Expression 1 distributes to the terms in Expression 2: x * (x + 3) and -5 * (x + 3), resulting in the same terms.

The operation of subtracting two polynomials is a closed system because when subtracting polynomials, the terms within each polynomial are combined and simplified, resulting in a polynomial expression that can be expressed as a polynomial.