When you are feeling lost solving inverse functions for your differential calculus class, the only way to see some rationale is to look through the questions and answers by taking a detailed approach. If it does not make much sense, you should use equations and graphs as you are proving inverse functions. It will help you to see where things get challenging as you can compare the questions to the answers provided. Just remember that the purpose here is to "undo" another function, which makes the function inverse. Once you learn to reverse-engineer, your general calculus challenges will get easier!