For this case we have the following function:
y = -6cos4x
The function is defined for all values of x, therefore, the domain is:
(-inf, inf)
The range of the function is:
For x = 0
y = -6cos (4 (0))
y = -6cos (0)
y = -6 (1)
y = -6
For x = pi / 4
y = -6cos (4 (pi / 4))
y = -6cos (pi)
y = -6 (-1)
y = 6
The range of the function is:
[-6, 6]
The amplitude of the function is:
6
Answer:
Domain: (-inf, inf)
Range: [-6, 6]
Amplitude: 6