Hi Jesse,

The Fundamental Theorem of Calculus is one of the foundational elements of Calculus that you will need to understand to learn Calculus. It has two components to it, and you can look here for some introductory information about it.

I took Algebra I and Geometry online in middle school so that I would be on course to take Calculus I towards the end of my high school career. While it can look intimidating at first, it mainly synthesizes knowledge from previous classes to understand some more practical ways you can use math.

Each class taken between Algebra I and Calculus is very important, and they provide several building blocks for calculus. Here are some examples:

• Geometry: introduction to sin, cos, tan, conic sections, circles
• Algebra II/Trigonometry: parent functions, the unit circle, polynomials, law of sin/cos
• Pre-Calculus: complex numbers, series, limits, practical uses of sin/cos/tan

I recommend you go through all of the Khan Academy courses fully, completing all of the modules between Algebra I and Calculus. This will take time, but it will lay the foundation you need to do well in Calculus and give you critical problem-solving skills to answer more complex problems Calculus might give you. Along the way, you may find some more challenging concepts to comprehend but they are necessary for you to understand and apply Calculus in the right mathematical situations.

There shouldn't be a need to purchase any textbooks — Khan Academy has great learning material (and hey, it's free), and your desire to succeed will be all you need.