Answer: See below:
Advantages as an equation: When you have an equation instead of a graph, you can use the equation to find exact values for a function. With a graph, don't always have the exact values. However, with an equation, you can find the exact input or output values.
Disadvantages as an equation: You don't get to see the overall picture or patterns in the function. With a graph, you can easily see the increasing and decreasing intervals of the function.