Here are the graphs of the functions:

1. $f(x) = 6^x$ (blue) – an exponential growth function, rapidly increasing as $x$ becomes positive.
2. $f(x) = 5^{-x}$ (red) – an exponential decay function, decreasing quickly as $x$ increases.
3. $f(x) = e^{-x}$ (green) – another exponential decay function, but less steep than the red curve due to the base $e$.

Each graph reflects either growth (for positive exponents) or decay (for negative exponents), depending on the function.

Would you like further details or have any questions?

Here are 5 related questions for deeper understanding:

1. How do exponential growth and decay functions behave as $x \to -\infty$?
2. What is the effect of changing the base of the exponent on the graph?
3. How do the graphs of $e^x$ and $e^{-x}$ compare?
4. What applications do exponential functions have in real-world scenarios?
5. How do exponential functions relate to logarithmic functions?

Tip: Exponential functions with negative exponents are always decreasing functions for $x > 0$.