Find the period, range, and amplitude of the cosine function. y = –3 cos 4x

We have the following function that has been plotted in the figure below:

So we need to find three characteristics of this functions, namely, its period, range and amplitude, so let's find out:

1. Period

Consider this equation:

The period of this function is given by:

2. Range

The range of a function is the set of outputs. Therefore, as shown in the figure the range of this function is:

3. Amplitude

The amplitude represents half the distance between the maximum and minimum values of the function and is given by:

First subtract 10 from both side
y^2+6y-16=0
(y+8)(y-2)=0
-8 and 2

Ibelieve the answer is c