Answer: Choice D
Maximums = (0,1) and (2pi, 1)
minimum = (pi, -3)
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Step-by-step explanation:
Cosine is a periodic function that bounces up and down forever. The highest y = cos(x) gets is y = 1 and that happens when x = 0, 2pi, etc. Basically anything in the form x = 2pi*n for any integer n will have y = cos(x) maxed out. Consequently, this means y = 2cos(x)-1 maxes out at the same mentioned x values.
Plug in those x values to find that y = 1 is the max y value for y = 2cos(x)-1
A similar situation happens for the mins as well. We have y = cos(x) be the smallest when x = pi+2pi*n for any integer n.