Answer:
81.68 is the correct answer. Hoped this helped.
 
        
             
        
        
        
You can make it easier by replacing x^n with another variable, factoring, then putting x^n back in the end. 
Using exponent and algebra rules, rewrite x^2n - 2x^n + 1 as 
(x^n)^2 - (2 x x^2) + 1
Then, let x^n = m.
m^2 - 2m + 1
Now factor that: (m - 1)^2
And now put x^n back: (x^n - 1)^2
        
             
        
        
        
18/30=?/100
18 times 100 = 1800
1800 divided by 30
60%
        
             
        
        
        
Since the square has 4 sides, you only have to add 

 four times.
The <span>perimeter of the square is: </span><span>

 cm </span>