graph the function y=-3 cos 2x.
to draw the graph, plot all points corresponding to x-intercepts, minima, and maxima within one cycle. then click on the graph icon.

  see the attachment for a graph

Step-by-step explanation:

You know the cos(θ) function has a maximum of 1 at θ=0 and 2π, and a minimum of -1 at θ=π. You know it has zeros at θ=π/2 and 3π/2. Here, θ=2x, so all of these θ-values will be cut in half to turn them into values for x.

Here, too, the function is multiplied by -3, so the maximum cos(2π)=1 becomes the minimum on your graph, -3cos(2x)=-3 where x=0 or π.