Please help! Will mark brainleist!

Below are two lengths of a triangle-
side one:-2x-1
side two: 9x+ -3
Perimeter: +-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?

Indicate the formula for the following conditions: p^c(n,r)=

Simplify (4x^2 - 8xy + 2y^2) - (9x^2 - 4xy - 7y^2) a. -5x^2 + 4xy + 9y^2 b. -5x^2 - 4xy + 9y^2 c. -5x^2 + 12xy + 4y^2 d. -5x^2 - 4xy - 5y^2

Unaware that 35% of the 10000 voters in his constituency support him, a politician decides to estimate his political strength. a sample of 200 voters shows that 40% support him. a. what is the population? b. what is the parameter of interest? state its value c. what is the statistics of the interest? state its value d. compare your answers in (b) and (c) is it surprising they are different? if the politician were to sample another 200 voters, which of the two numbers would most likely change? explain