
Let the two adjacent sides of the rectangle as
l = 2x2 – 5xy + 3z2 and b = 4xy – x2y + 3z2
Perimeter of the rectangle
= 2(l + b)
= 2(2x2 – 5xy + 3z2 + 4xy – x2 – z2)
= 4x2 – 10xy + 6z2 + 8xy – 2x2 – 2z2
= 4x2 – 2x2 – 10xy + 8xy + 6z2 – 2z2
= x2(4 – 2) + xy (-10 + 8) + z2 (6 – 2z2)
Perimeter = 2x2 – 2xy + 4z2
Degree of the expression is 2.