Answer:
y = 3sin2(x - pi)
Explanation:
The number in front of the trigonometric value (sin, cos, tan, etc.) indicates the amplitude. If the period is pi then the value in front of x must be 2, because frequency (in other words, the period) is determined by the equation 2pi/B, where the value in front of (x) is B. And if the phase shift is pi, or positive pi, then the corresponding equation must be (x - pi) because it's always the opposite.