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miley23
Identify the maximum and minimum values of the function y = 3 cos x in the interval [-2π, 2π].
3cosx has period 2pi, (just like cosx). The domain here is 2 periods, so we can be sure there are min and max values. cosx has values between -1 and 1, with -1 and 1 as min and max values. Now ask yourself this question: what is the effect of the factor 3 on this?
maximum value is 3 and minimum is -3 because maximum and minimum of cosx is 1 and -1.