Answer:
The value of the Rational expression when
is: 
Step-by-step explanation:
For this exercise is important to remember:
- When a negative number is raised to an even power, the result will be positive.
- The multiplication of signs:

Then, given the following Rational expression:

You need to follow these steps in order to find its value when
:
1. Substitute the given value of "x" (
) into the expression:

2. Evaluate and simplify:

Answer: 
Step-by-step explanation:
If the volume of a sphere is

Where
is the radius
The volume of a hemisphere is half the volume of the total sphere:


Solving this equation:

Finally:

The equation is y = 1/2 x + 13, where x is the number of days, and y is the length of the barrier