Answer:
x-axis
Step-by-step explanation:
The asymptote is a straight line that the curve gets closer and closer to but never touches it.
The given exponential function is [tex]f(x)=3^x[/tex].
The given graph has a horizontal asymptote,
The equation of this horizontal asymptote is y=0.
This is also refers to as the x-axis.
Therefore the asymptote is the x-axis.
