Trig graph shifts

So the problem is:
http://www.imathas.com/cgi-bin/mimet...ht%29%7D%7D%7D
Find the amplitude, period and phase shift and then graph the function.
http://www.imathas.com/cgi-bin/mimet...C%7D%3D%7B2%7D
http://www.imathas.com/cgi-bin/mimet...ight.%7D%7D%7D
http://www.imathas.com/cgi-bin/mimet...%5Cright%29%7D
So the answer in the book has these answers as http://www.imathas.com/cgi-bin/mimet...D%7B%7B6%7D%7D
My question is, where did the negative come from for the phase shift?

Quote:

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Originally Posted by xsavethesporksx

So the problem is:
http://www.imathas.com/cgi-bin/mimet...ht%29%7D%7D%7D
Find the amplitude, period and phase shift and then graph the function.
http://www.imathas.com/cgi-bin/mimet...C%7D%3D%7B2%7D
http://www.imathas.com/cgi-bin/mimet...ight.%7D%7D%7D
http://www.imathas.com/cgi-bin/mimet...%5Cright%29%7D
So the answer in the book has these answers as http://www.imathas.com/cgi-bin/mimet...D%7B%7B6%7D%7D
My question is, where did the negative come from for the phase shift?

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A simple way to understand it is to consider this:

A parabola with equation is shifted 3 units right from the origin.

A parabola with equation is shifted 3 units left fom the origin.

Think about it.

so same concept... just change the sign and shift it

I think that I over thought that one a bit.

Thanks