Which of the following functions illustrates a change in amp

Which of the following functions illustrates a change in amplitude y = 1 + xin times y = 2cos 6 times y = tan 2x y = -2 - cos (X - Pie)

Solution

you have the function : f(x)= Asin(Bx+C)+D where A is the amplitude so, if you have :

y=-2cos(6x), the amplitude of this function is 2, It is the only function of all that has a change of amplitude

So, the answer is the letter (B)