Any area of math like Calculus, algebra, or trigonometry is a house that cannot be built on moving sand. First, aim for the foundation. If the formulas are beyond your grasp, and you are unable to calculate and chart at a fast pace, you might be having difficulties for sure. Thus, make sure you practice these necessary abilities sufficiently so that you can use them precisely and quickly while still having mental stamina to spare for new information. In this instance, it can be highly helpful to work on you a little bit each day and to challenge yourself to be more responsive and precise. There are some textbooks and online services like
Take My Online Calculus Class that provide resources to help you review your pre-calculus and base of the mathematics.