Answer:
x =-4
Step-by-step explanation:
4x+9 = -2x-15
Add 2x to each side
4x+2x +9 = -2x+2x-15
6x+9 = -15
Subtract 9 from each side
6x +9-9=-15-9
6x = -24
Divide each side by 6
6x/6 = -24/6
x = -4
Given the function:

Let's find the amplitude and period of the function.
Apply the general cosine function:

Where A is the amplitude.
Comparing both functions, we have:
A = 1
b = 4
Hence, we have:
Amplitude, A = 1
To find the period, we have:

Therefore, the period is = π/2
The graph of the function is shown below:
The parent function of the given function is:

Let's describe the transformation..
Apply the transformation rules for function.
We have:
The transformation that occured from f(x) = cosx to g(x) = cos4x using the rules of transformation can be said to be a horizontal compression.
ANSWER:
Amplitude = 1
Period = π/2
Transformation = horizontal compression.
(0.00142857)=-x is your answer