Sketch the graph of $y=x^2-9$.  

1. State the coordinates of the $y$-intercept. What is the connection between the $y$-intercept and the equation $y=x^2-9$?

   Answer (a):

   The $y$-intercept is where $x = 0$.
   $y=\left(0\right)^2-9$

2. State the coordinates of the $x$-intercepts. What is the connection between the $x$-intercepts and the equation $y=x^2-9$?

   Answer (b):

   The $x$-intercepts are where $y = 0$.
   $0=x^2-9$