## Precalculus (6th Edition) Blitzer

Step 1. Graph equations $\frac{x^2}{4}-\frac{y^2}{9}=1$ (red) and $\frac{x^2}{4}-\frac{y^2}{9}=-1$ (blue) as shown in the figure. Step 2. We can see that they have different transverse axes with exchanged $a, b$ values.