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.

Answer 1

@undeadknight26

Answer 2

I believe the equation is:
8x^2 - 5x - 2 + 7x - x^2 + 3 + x = 4x^3 - 3x^2 + 2x - 6

Answer 3

Then you get -4x^3 + 10x^2 + x + 7?

Answer 4

I don't think so, let me check.

Answer 5

Add sides 1 and 2, then subtract that sum from the given perimeter to find side 3.

Answer 6

Oh yeah, duh! I'm so dumb sometimes.

Answer 7

8x^2 - 5x - 2 + 7x - x^2 + 3
7x^2 + 2x + 1

Answer 8

So thats the sum from 1 and 2?

Answer 9

Yeah

Answer 10

4x^3 - 3x^2 + 2x - 6 -(7x^2 + 2x + 1)

Answer 11

You have to distribute the -.

Answer 12

So 4x^3 - 3x^2 + 2x - 6 - 7x^2 - 2x - 1

Answer 13

Can you solve it from there?

Answer 14

No

Answer 15

Alright, combine like terms.
4x^3 = 4x^3
-3x^2 - 7x^2 =
2x - 2x =
-6 - 1 =

Answer 16

ok do you still solve from -6 - 1?

Answer 17

Yeah...

Answer 18

Why wouldn't you?

Answer 19

I dont know im so horrible at math its not even funny

Answer 20

so its -5

Answer 21

No, -6 - 1 does not = -5. You are subtracting 1 from -6.

Answer 22

oh -7

Answer 23

Correct, so what do you have for the others?

Answer 24

4x^3 = 4x^3
-3x^2 - 7x^2 =
2x - 2x =
-6 - 1 = -7

Answer 25

okay

Answer 26

brb

Answer 27

I'm back.

Answer 28

Have you figured it out?

Answer 29

Yes i did thank you

Answer 30

Awesome. :D