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?

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.

Question

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? 

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.

meowlover17 · Answer

@welshfella

hero · Answer

@MeowLover17, What is (8x^2 - 5x - 2) + (7x - x^2 + 3) ?

meowlover17 · Answer

One moment

jhannybean · Answer

Rearrange your terms to combine like terms with eachother. It makes it easier to evaluate.

meowlover17 · Answer

I got +6x^2+2x+1 @Hero

meowlover17 · Answer

Sorry my computer died

meowlover17 · Answer

@Jhannybean

meowlover17 · Answer

Hello hero i got what i wrote above

meowlover17 · Answer

So would that be the total length of the two sides??

hero · Answer

You should have gotten 7x^2 + 2x + 1

meowlover17 · Answer

Oh sorry yes i see

meowlover17 · Answer

So hero 7x^2 + 2x + 1 <- This is my answer for part A correct?

meowlover17 · Answer

how would i find the length of the third side?

hero · Answer

To find the length of the third side subtract the result you got for part A from the perimeter.

meowlover17 · Answer

That's what i was thinking let me do that

meowlover17 · Answer

so i would receive -4x^3+10^2+7?

meowlover17 · Answer

for the length of the third side

hero · Answer

Subtract this way:

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