We're choosing among
and we have to figure out which signs goes with which graph.
If they're both positive we have a pretty normal exponential,
That's going to be zero as x gets negative and exponentially explode toward positive infinity for positive x. Graph 3.
That's the same as the last one except it goes to negative infinity. It's the last one reflected in the x axis. Graph 4.
When we have a fraction between 0 and 1 for the base as x gets bigger this goes to zero and as x gets more negative, this diverges toward positive infinity. It's our first graph reflected in the y axis, the same as
. That's our first graph reflected in the y axis. Graph 1.
That's the same as
. As x gets more negative y diverges toward negative infinity. Graph 2.