Question 11060
The y-intercept for {{{y = x^3 - 3}}} is found by setting x = 0.

{{{y = (0)^3 - 3}}}
{{{y = -3}}} The y-intercept is at (0, -3)

The vertex? This question would make sense for a quadratic equation, but you have a cubic (third degree) equation and these have no vertex (maximum or minimum).  The best you can do for a cubic function is to find the relative maximum or relative minimum, if there is one.
Take a look at the grah of this function and you'll see what I mean.

{{{graph(300,200,-5,5,-5,5,x^3-3)}}}

You can see that the y-intercept is (o, -3) but the vertex?

Perhaps you meant to type: {{{y = x^2 - 3}}} ??

Let's see what that looks like.

{{{graph(300,200,-5,5,-5,5,x^2-3)}}}

The y-intercept is found, as before, by setting x = 0.

{{{y = (0)^2 - 3}}}

The y-intercept is at (0, -3) as you can see on the graph.

The x-coordinte of the vertex is found by:
 {{{x = -b/2a}}}
{{{x = -(0)/2}}}
{{{x = 0}}} and the y-coordinate of the vertex is found by substituting this value of x into the original equation and solving for y.

{{{y = (0)^2 - 3}}}
{{{y = -3}}}

The y-coordinate is y = -3.

So the vertex is at (0, -3)