What is the equation of the midline for the function f (x)?
f (t) = 3 cos (x) – 2.5

  y = -2.5

Step-by-step explanation:

For such a problem as this, you can replace all sine or cosine functions with their midline value of 0. Then you have ...

  f(x) = 0 -2.5

which simplifies to ...

  f(x) = -2.5

You can leave the equation like this, or write it as ...

  y = -2.5

Perhaps you can see that the midline is the value of any constant added to a sine or cosine function.

f(x) = x^3 -2x^2 -3x

x( x^2 -2x-3)

x( x^2 +x -3x -3)

x( x(x+1) -3(x+1))

x( x-3)( x+1)

so zeroes are 0, 3,-1

its (2) option