Question

Consider the function y = 2cos(-x)-4. What effect does "-x" have on the basic graph?

A)Flip over the vertical axis
B)Horizontal shift left 1
C)Vertical shift down 1
D)Flip over horizontal axis

Answer 1

A)

But really there is no effect since cos(-x)=cos(x).

Explanation:

Cosine is an even function.

Even functions are symmetric about the y-axis.

So really for cosine; cos(-x) has no change to cos(x) since they are equal.

But if you keep in mind that cosine is symmetric about the y-axis, then it has been reflected over the y-axis; this is the vertical axis.

A)