# Exponential Expressions

1.   $\rhd$ Introduction to exponential functions (7:40)  Sal investigates a function where the variable is in the exponent, rather than the base.  In particular, he computes a table of values for $y = 3^x$ and uses that table of values to sketch a graph.  He also uses a chain letter as an example of an exponential function.
2.   $\rhd$ Initial value and common ratio of exponential functions (5:26)  Using examples $h(n) = \frac{1}{4} \cdot 2^n$ and $f(t) = 5 \cdot 3^t$, learn about the initial value and the common ratio.
3.  $\rhd$ Finding the equation of an exponential function from a graph (7:37)  Sal finds the equation of an exponential function using two points on the graph and the general form of the equation of an exponential function: $g(x) = a \cdot r^x$.