To graph Vab as a function of current (I), an explicit relationship or additional data is necessary due to the infinite possible functions that could satisfy the conditions. Users are seeking methods to perform this graphing on a TI-84 Plus calculator. Without a defined equation or dataset, it is challenging to create a meaningful graph. The discussion emphasizes the importance of having a clear rule or data to accurately represent the relationship. Ultimately, a well-defined function is essential for effective graphing.