Which description matches the transformations y=cos x undergoes to produce y=3cos (-2x)?

Please explain. Thank you!

Question

Which description matches the transformations y=cos x undergoes to produce y=3cos (-2x)?

Please explain. Thank you!

kj4uts · Answer

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stamp · Answer

I recommend reading your textbook, to understand the properties of trig functions. There will be a portion that discusses what kind of changes will take place when the coefficient is adjusted, or what changes will take place when the inside of the trig function is adjusted. Otherwise, compare the graphs of the functions cosx, cos(-2x), and 3cosx. I graphed them online and they can be seen here: http://www.wolframalpha.com/input/?i=graph+cosx%2C+3cosx%2C+cos%28-2x%29

kj4uts · Answer

I was thinking C.

kj4uts · Answer

a. and d. have to do with horizontal shifts which I don't see any

stamp · Answer

http://www.wolframalpha.com/input/?i=graph+cosx%2C+3cos%28-2x%29 Here is a graph of cosx and 3cos(-2x). I agree with answer choice C, as well as your eliminations of answer choices A. and D.