Question

I am of need of HELP. I am working on the word problems for AXIA math 117 and I do not understand the first problem. I have listed the information below. I have tried many times and I have not figured this out. My assignment is due tomorrow and I am desperate for help with work shown so I can understand. There is multiple parts and I only copied part of it.
The cost, in millions of dollars, to remove x % of pollution in a lake modeled by the equation C=6,000/200-2x^2

What is the cost to remove 20% of the pollutant?

Please help! Thanks!

Answer 1

First of all, I don't think you meant to type the equation as you did, or else why not reduce it to
C = 3000 - 2x^2

So I will assume you meant
C = 6000/(200-2x^2)

Secondly, the way you defined x % , we would have to replace x with 20, and then your result would be
C = 6000/(200 - 800) which will result in a negative cost, thus making no sense.

If we replace 20% with 0.2, we would get
C = 6000/(200 - .08) = 30.012

but the cost of removing 90% would then be
6000/(200 - 1.62) = 30.24
which is only slightly higher than removing 20%.
This does not make sense to me, so please check the typing of the equation, and the definition of x