Expert: Richard J. Raridon - 9/8/2010

Question
x2=y2-4     Sketch the graph, identify intercepts, and test for symmetry.  I
calculated the x-int. to be +- 2i and the graph is symmetric about the x/y-axis
and the origin.  Is my math correct and how can I graph this equation?

Answer
You can write it y^2 = x^2+4
Since 2i is imaginary, you just showed that there's no x-intercept.  
I can't sketch the graph for you but it's easy to do.  Just put in a value for x, calculate the two values for y, and plot both of them.  
Obviously, for x=0, y= +/-2