Which of the following could be the equation of the function below?

Step-by-step explanation:

From the graph, we can see that y = -3 when x  = 0.

So to check whether which of the given options is the equation of the given graph, we will set our calculator to the radian mode and then plug the value of x as 0.

1. y = -2 cos (4(x + pi)) - 1 = -2 cos (4(0 + pi)) - 1  = 3

2. y = 2 cos(x + pi) = 2 cos(0 + pi) = -1

3. y = -2 cos (2(x + pi)) - 1 = -2 cos (2(x + pi)) - 1 = -3

Therefore, the equation of this graph is  y = -2 cos (2(x + pi)) - 1.