Please help! Will mark brainleist!

Below are two lengths of a triangle-
side one:3x^{2}-2x-1
side two: 9x+ 2x^{2}-3
Perimeter: 5x^{3}+4x^{2}-x-3
part a- What are the two sides of the triangle (show work).
Part b- What is the length of the third side (show work and reasoning).
part c- Do answers for a and b show the polynomials are closed under addition and subtraction?

29 is the correct answer

step-by-step explanation:

5=812a+9+3

step 1: simplify both sides of the equation.

5=812a+9+3

5=(812a)+(9+3)(combine like terms)

5=812a+12

5=812a+12

step 2: flip the equation.

812a+12=5

step 3: subtract 12 from both sides.

812a+12−12=5−12

812a=−7

step 4: divide both sides by 812.

812a /812 = -7/812

a= -1/116

so the answer is

a=   -1/116

answer: input the dimensions of the room to be painted. click the button to calculate the amount of paint and man-hours needed for this job.

interior paint coverage depends on the brand of paint used. the coverage amount is listed on the label of the paint can. use this to adjust the values in the paint coverage section below. paint usually is applied at 350 to 400 square feet per gallon (primer at 200 to 300 square feet per gallon).

step-by-step explanation: