Question

Algebra 1, please help! I'll give whoever helps me out a medal. :)

Answer 1

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

Side 1: 3x^2 - 4x - 1
Side 2: 4x - x^2 + 5

The perimeter of the triangle is 5x^3 - 2x^2 + 3x - 8.

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

Part B: What is the length of the third side of the triangle?

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

Answer 2

for Part A
simplify: 3x^2 - 4x - 1 + 4x - x^2 + 5 (add/subtract like terms)

Answer 3

Got it. :) How would I solve Part B? I'm kind of confused.. :/

Answer 4

perimeter of triangle = all sides added up
so third side = (perimeter) minus (other two sides)
so third side --> 5x^3 - 2x^2 + 3x - 8 - (what you got in part A)
and don't forget to distribute the negative^ when simplifying! :)

Answer 5

Thanks so much! :)

Answer 6

you're welcome :)

Answer 7

@jigglypuff314 About Part C.. I'm stuck on it. :( Could you help me out?

Answer 8

I'm not good with math vocab so I had to look it up..
http://learnzillion.com/lessonsets/441-understand-closure-of-sets-of-polynomials-under-addition-subtraction-and-multiplication-perform-these-operations-on-polynomials
those videos should help...
From what I understand: Yes, the answers for Part A and Part B show that the polynomials are closed under addition and subtraction.
(I'm not sure if this is correct but) because when the polynomials are added and subtracted, they result into polynomials...

Answer 9

Thanks again! :) I'll use the link.

Answer 10

glad I could help :)