Ok, so dy/dx=0 at the point (0,3) that is where x=0 and y=3.


Now, f'(x)=0 when x=0.
Therefore:

Now:


But when x=0, y=3, therefore:
Answer:
The cost of making 60 calls a month is $20.
Step-by-step explanation:
There was a small typing mistake there. If the fixed charge is $14, the cost of n calls is given by the following equation:

Find the cost of making 60 calls a month.
This is C(60), that is, C when n = 60. So


The cost of making 60 calls a month is $20.
Answer: 
<u>Step-by-step explanation:</u>
![12cos\bigg(\dfrac{2\pi}{5}x\bigg)+10=16\\\\\\12cos\bigg(\dfrac{2\pi}{5}x\bigg)=6\\\\\\cos\bigg(\dfrac{2\pi}{5}x\bigg)=\dfrac{1}{2}\\\\\\cos^{-1}\bigg[cos\bigg(\dfrac{2\pi}{5}x\bigg)\bigg]=cos^{-1}\bigg(\dfrac{1}{2}\bigg)](https://tex.z-dn.net/?f=12cos%5Cbigg%28%5Cdfrac%7B2%5Cpi%7D%7B5%7Dx%5Cbigg%29%2B10%3D16%5C%5C%5C%5C%5C%5C12cos%5Cbigg%28%5Cdfrac%7B2%5Cpi%7D%7B5%7Dx%5Cbigg%29%3D6%5C%5C%5C%5C%5C%5Ccos%5Cbigg%28%5Cdfrac%7B2%5Cpi%7D%7B5%7Dx%5Cbigg%29%3D%5Cdfrac%7B1%7D%7B2%7D%5C%5C%5C%5C%5C%5Ccos%5E%7B-1%7D%5Cbigg%5Bcos%5Cbigg%28%5Cdfrac%7B2%5Cpi%7D%7B5%7Dx%5Cbigg%29%5Cbigg%5D%3Dcos%5E%7B-1%7D%5Cbigg%28%5Cdfrac%7B1%7D%7B2%7D%5Cbigg%29)

Answer:
just want your points
Step-by-step explanation: