# Introduction to Applied Calculus

# About This Book

This textbook was created through Connecting the Pipeline: Libraries, OER, and Dual Enrollment from Secondary to Postsecondary, a $1.3 million project funded by LOUIS: The Louisiana Library Network and the Institute of Library and Museum Services. This project supports the extension of access to high-quality post-secondary opportunities to high school students across Louisiana and beyond by creating materials that can be adopted for dual enrollment environments. Dual enrollment is the opportunity for a student to be enrolled in high school and college at the same time.

The cohort-developed OER course materials are released under a license that permits their free use, reuse, modification and sharing with others. This includes a corresponding course available in Moodle and Canvas that can be imported to other platforms. For access/questions, contact Affordable Learning Louisiana.

If you are adopting this textbook, we would be glad to know of your use via this brief survey.

## Cover Image

The cover image is “Fibonacci spiral” by heroix and licensed in the Public Domain (Creative Commons PDM 1.0 DEED).

# How Is Applied Calculus Different?

Students who plan to go into science, engineering, or mathematics take a year-long sequence of classes that cover many of the same topics as we do in our one-quarter or one-semester course.

Here are some of the differences:

## No Trigonometry

We will not be using trigonometry at all in this course. The scientists and engineers need trigonometry frequently, and so a great deal of the engineering calculus course is devoted to trigonometric functions and the situations they can model.

## The Applications Are Different

The scientists and engineers learn how to apply calculus to physics problems, such as work. They do a lot of geometric applications, like finding minimum distances, volumes of revolution, or arclengths. In this class, we will do only a few of these (distance/velocity problems, areas between curves). On the other hand, we will learn to apply calculus in some economic and business settings, like maximizing profit or minimizing average cost, finding elasticity of demand, or finding the present value of a continuous income stream. Additionally, we will apply calculus in life and social science settings, like determining the rate at which drug concentration in the body is changing, or exploring the rate at which a subject learns. These are applications that are seldom seen in a course for engineers.

## Fewer Theorems, No Proofs

The focus of this course is applications rather than theory. In this course, we will use the results of some theorems, but we won’t prove any of them. When you finish this course, you should be able to solve many kinds of problems using calculus, but you won’t be prepared to go on to higher mathematics.

## Less Algebra

In this class, you will not need clever algebra. If you need to solve an equation, it will either be relatively simple, or you can use technology to solve it. In most cases, you won’t need “exact answers”; calculator numbers will be good enough.

# Simplification and Calculator Numbers

When you were in tenth grade, your math teacher may have impressed you with the need to simplify your answers. I’m here to tell you – she was wrong. The form your answer should be in depends entirely on what you will do with it next. In addition, the process of “simplifying” often messy algebra can ruin perfectly correct answers. From the teacher’s point of view, “simplifying” obscures how a student arrived at his answer and makes problems harder to grade. Moral: don’t spend a lot of extra time simplifying your answer. Leave it as close to how you arrived at it as possible.

## When Should You Simplify?

- Simplify when it actually makes your life easier. For example, in Chapter 2 it’s easier to find a second derivative if you simplify the first derivative.
- Simplify your answer when you need to match it to an answer in the book. You may need to do some algebra to be sure your answer and the book answer are the same.

## When You Use Your Calculator

A calculator is required for this course, and it can be a wonderful tool. However, you should be careful not to rely too strongly on your calculator.

Follow these rules of thumb:

- Estimate your answers. If you expect an answer of about 4, and your calculator says 2500, you’ve made an error somewhere.
- Don’t round until the very end. Every time you make a calculation with a rounded number, your answer gets a little bit worse.
- When you answer an applied problem, find a calculator number. It doesn’t mean much to suggest that the company should produce [latex]\frac{\sqrt{2100}\left(2.4\right)}{2.5}[/latex] items; it’s much more meaningful to report that they should produce about 106 items.
- When you present your final answer, round it to something that makes sense. If you’ve found an amount of US money, round it to the nearest cent. If you’ve computed the number of people, round to the nearest person. If there’s no obvious context, show your teacher at least two digits after the decimal place.
- Occasionally in this course, you will need to find the “exact answer.” That means – not a calculator approximation. (You can still use your calculator to check your answer.)