Answer:
Option B is correct
Step-by-step explanation:
Given is a cos funciton.
Period = 3
Max = 20 and minimum =0
Hence centre line is y = 1/2 (max+min)
i.e. y =10 is the central line
Let the funciton be of the form
y = a cos (bx+C)+d
We got d = 10...i
Period =3
Hence b =
... ii
Amplitude = a = distance of max from central line = 20-10 =10...iii
Since reflection over x axis, sign of a =negative
a=-10
Since no horizontal shift, c=0 ... iv
Put to gether the function is

A reflection over the x-axis only change the signal of the coordinate y of the point. Hence, the coordinates of vertex B' are:

.
I’m not very good at math but I think it’s C but i could be wrong though.
You didnt list any graph?? Can you add it please :)
<span> f(x) = –81 (4/3) X-1 f(x) = –81 (-3/4) </span>