Determine the amplitude and period of the following function without graphing.
y = -7cos(9x)
show your work.
The general form of the cosine function is y = A*cos(B(x-h)) + k, where A is the amplitude, B is the period, h is the phase shift, and k is the vertical shift.
In the given function y = -7cos(9x), we have:
A = -7 (amplitude)
B = 9 (period)
Therefore, the amplitude is -7 and the period is 2π/B = 2π/9.