The lengths of three sides of a quadrilateral are shown below:

side 1: 3y2 + 2y − 6

side 2: 3y − 7 + 4y2

side 3: −8 + 5y2 + 4y

the perimeter of the quadrilateral is 4y3 + 18y2 + 16y − 26.

part a: what is the total length of sides 1, 2, and 3 of the quadrilateral? (4 points)

part b: what is the length of the fourth side of the quadrilateral? (4 points)

part c: do the answers for part a and part b show that the polynomials are closed under addition and subtraction? justify your answer. (2 points)