difference between y=AsinB(x+C)+D and y=Asin(Bx-C)+D

Question

my maths assignment asks 

The function y=A Sin(Bx+C)+D has been used by your Graphics calculator in determining a Sinusoidal/Periodic regression. According to the Maths B syllabus, it is written in the form
y=A Sin B(x+C)+D.
Justify when you would use one form over another form.

Answer 1

y=A Sin(Bx+C)+D, B multiplies only x. The period is 2π/B, phase shift is -C/B

y=A Sin B(x+C)+D, B multiplies both x and C ⇒

y=A Sin (Bx+BC)+D, The period is the same, yet the phase shift is -BC/B = -C