Final answer:
Without specifics about the graph, we can't identify Sadie's equation, but we described the process of graphically solving an equation and the importance of checking solutions analytically for greater accuracy.
Step-by-step explanation:
To determine what equation Sadie solved using a graph, we would need specific information about the graph, such as the shape of the curve, the axes, and any marked points or intersections. However, we can discuss the general process of using graphs to solve equations.
Firstly, Sadie would identify the knowns and the unknowns from the given problem. Next, she would select and write down the appropriate equation to use. After ensuring all values are in the correct units, she would graph the functions represented by the equation. The solution to the equation could then be found where these functions intersect on the graph. Lastly, she would verify her solution by substituting it back into the original equation to see if it makes logical sense or by comparing the graphically obtained solution to one found analytically, if possible.
Graphical methods are useful for visualizing solutions, but it's important to note that analytical techniques are often more accurate as they involve precise calculations rather than estimations based on a graph.