Question

Just need help for part C. I listed the answers for Part A and B if it helps.

please explain ur answer

The lengths of two sides of a triangle are shown below:


Side 1: 8x2 − 5x − 2


Side 2: 7x − x2 + 3


The perimeter of the triangle is 4x3 − 3x2 + 2x − 6.


Part A: What is the total length of the two sides, 1 and 2, of the triangle? (4 points)

answer: 7x^2 + 2x + 1


Part B: What is the length of the third side of the triangle? (4 points)

Answer: 4x^3 - 10x^2 - 7


Part C: Do the answers for Part A and Part B show that the polynomials are closed under addition and subtraction? Justify your answer. (2 points)

Answer 1

Yes.

Explanation:

"closed under addition and subtraction" means that if you add (or subtract) two polynomials, you get a polynomial**. If they mean does your work PROVE it, well, it does NOT prove it. But it is a good example showing that:

when you add (or subtract) polynomials, the result is also a polynomial.

**polynomial is an expression like 8x^2-5x-2 or

7-x^2+3 or

4x^3-10x^2-7