# 1: Limits

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So very roughly speaking, “Differential Calculus” is the study of how a function changes as its input changes. The mathematical object we use to describe this is the “derivative” of a function. To properly describe what this thing is we need some machinery; in particular we need to define what we mean by “tangent” and “limit”. We'll get back to defining the derivative in Chapter 2.

• 1.1: Drawing Tangents and a First Limit
Now — our treatment of limits is not going to be completely mathematically rigorous, so we won't have too many formal definitions. There will be a few mathematically precise definitions and theorems as we go, but we'll make sure there is plenty of explanation around them.
• 1.2: Another Limit and Computing Velocity
Computing tangent lines is all very well, but what does this have to do with applications or the “Real World”? Well - at least initially our use of limits (and indeed of calculus) is going to be a little removed from real world applications. However as we go further and learn more about limits and derivatives we will be able to get closer to real problems and their solutions.
• 1.3: The Limit of a Function
Before we come to definitions, let us start with a little notation for limits.
• 1.4: Calculating Limits with Limit Laws
Think back to the functions you know and the sorts of things you have been asked to draw, factor and so on.
• 1.5: Limits at Infinity
Up until this point we have discussed what happens to a function as we move its input $$x$$ closer and closer to a particular point $$a\text{.}$$ For a great many applications of limits we need to understand what happens to a function when its input becomes extremely large
• 1.6: Continuity
We have seen that computing the limits some functions — polynomials and rational functions — is very easy because
• 1.7: (Optional) — Making the Informal a Little More Formal
As we noted above, the definition of limits that we have been working with was quite informal and not mathematically rigorous. In this (optional) section we will work to understand the rigorous definition of limits.
• 1.8: (Optional) — Making Infinite Limits a Little More Formal
For those of you who made it through the formal $$\epsilon-\delta$$ definition of limits we give the formal definition of limits involving infinity:
• 1.9: (Optional) — Proving the Arithmetic of Limits
Perhaps the most useful theorem of this chapter is Theorem 1.4.3 which shows how limits interact with arithmetic. In this (optional) section we will prove both the arithmetic of limits Theorem 1.4.3 and the Squeeze Theorem 1.4.18.

This page titled 1: Limits is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Joel Feldman, Andrew Rechnitzer and Elyse Yeager via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.