Answer:
13.15
Step-by-step explanation:
General vertex form:

Given :

Extract "spread factor" m

Complete the square


Write as a squared binomial and simplify the constant

Re-write to match signs of standard general form:

Answer:
4x + 28.4 in.
Step-by-step explanation:
perimeter = sum of lengths of sides
perimeter = x + 2 + x + 2 + x + 2 + x + 2 + 10.2 + 10.2
perimeter = 4x + 28.4