Algebra homework

Question

Please! Write an equation for the cosine function with an amplitude of 3, a period of 2, a phase shift of 7, and a vertical displacement of -1.

A. Y=3cos2π(x-7)/2 -1

B. Y=3cos2(x-7)+1

C. Y=-3cos2π(x-7)-1

D. Y=-3cos2(x+7)+1

Answer 1

y = A cos[(2π/T)(x - φ)] + y₀

A = amplitude = 3

T = period = 2

φ = phase shift = 7

y₀ = vertical displacement = -1

Plug in the values and get

y = 3 cos[(2π/2)(x - 7)] - 1

It looks like (A) is the right answer.