We know that the population is declining at a rate of 14% per year.
The expression is: 
N ( x ) = 206 * ( 0.86 ) ^ x
where x stays for years.
If we want to find the rate at which the population is declining per month we have to find:
![\sqrt[12]{0.86} = 0.9875](https://tex.z-dn.net/?f=%20%5Csqrt%5B12%5D%7B0.86%7D%20%3D%200.9875%20%20)
And 0.9875 ≈ 0.99
There are 12 months in a year so the exponent is: x/12
Answer:
b. ( .99 ) ^ x/12
 
 
        
                    
             
        
        
        
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Check the picture below.  Recall, is an open-top box, so, the top is not part of the surface area, of the 300 cm².  Also, recall, the base is a square, thus, length = width = x.

so.. that'd be the V(x) for such box, now, where is the maximum point at?

now, let's check if it's a maximum point at 10, by doing a first-derivative test on it.  Check the second picture below.
so, the volume will then be at   
 
 
        
        
        
To calculate distance between two points we use the distance formula sqrt((x2−x1)^2+(y2−y1)^2).  
To start, we find the square of the distance between x1 and x2 and y1 and y2.  The distance between x1 and x2, or 1 and 3, is 2. The distance between y1 and y2, or 3 and -4, is 7.
Now we square 2 and 7 and add them together to get 4 + 49 = 53.
The last thing we do to find the distance is take the square root of 53. 53 is not a perfect square and is also a prime number so our answer in simplest form is still sqrt53.<span />