### Exploring Types of Discontinuities: AP Calculus AB/BC Study Guide

#### Introduction to Discontinuities

Howdy, mathletes and calculus adventurers! 🌟 Welcome to the discontinuity zone, where we'll explore the roller coaster of functions that just don't play by the rules. Continuity in mathematics is like a perfect symphony; everything flows seamlessly without interruption. But what happens when the music stops, and you need to restart the record? That's where discontinuities come into play 🎶🔄.

For a function to be continuous, it must tick three essential boxes:

- It's defined for every value of ( x ).
- It has a defined limit at every point.
- The left-hand limit and the right-hand limit agree like best friends at each point.

But sometimes, the symphony hits a discordant note. A discontinuity is any point where the function decides to bail on continuity. Imagine drawing your function graph and having to lift your pencil. That's your discontinuity! ✏️ Now, let's take a closer look at the different types of discontinuities, served with a side of humor.

#### Removable Discontinuities (AKA the "Oops, There's a Hole" Discontinuity)

Removable discontinuities are like potholes on a smooth road. They're single points where the function is technically undefined, but the limit still exists. They're also called "holes" because there's just a teeny-weeny gap where the function should have been.

Picture this: You're driving smoothly on your skateboard track 🎿, but suddenly you have to jump over a tiny hole. That's your removable discontinuity! To represent this graphically, you draw the function as usual but leave an empty circle where the point is missing.

##### Example Time! 🚀

Try this piecewise function: [ y = \begin{cases} x^2 & \text{if } x < 1 \ x - 1 & \text{if } x = 1 \ -x + 2 & \text{if } x > 1 \end{cases} ]

The function dips and dives but isn't defined at ( x = 1 ). Instead, you see an empty circle there—your skateboard jumps over a pothole!

But why does this happen? Sometimes it’s a small "blip," and other times it’s due to a factor in a fraction. Take the function ( y = \frac{x^3 - 3x^2 + 2x}{x - 1} ) for ( 1 > x > 1 ), and ( y = x ) if ( x = 1 ). Factor out the numerator to see the hidden removable discontinuity!

#### Jump Discontinuities (AKA the "Leap of Faith" Discontinuity)

Jump discontinuities are like cliffs in a video game. You're merrily navigating your character when, bam, there's a chasm you need to leap across! 😱 Mathematically, this happens when the left-hand limit and right-hand limit disagree, resulting in a sudden vertical "jump."

##### Time to Jump! 🏃♂️

Consider this function: [ y = \begin{cases} x - 2 & \text{if } x \leq 3 \ x + 1 & \text{if } x > 3 \end{cases} ]

At ( x = 3 ), you have two circles: one filled, one open. The "leap" between these points represents your jump discontinuity. Your character jumps up (or down) to meet the other side.

#### Asymptote Discontinuities (AKA the "Endless Chase" Discontinuity)

Asymptote discontinuities are the ultimate game of chicken. You're driving two cars towards each other, slamming the brakes inches apart, but never quite touching. These occur when the limits on either side of a point approach infinity (positive or negative).

##### The Cuckoo Asymptote! 🚗💨

Draw the simple function ( y = \frac{1}{x} ). As ( x ) approaches 0, the graph rockets off to infinity and negative infinity, creating a vertical asymptote. They rush towards the center but never quite collide!

#### Recap: How to Identify Discontinuities 📝

Now, let's recap the essentials for identifying discontinuities:

**Removable Discontinuities**

- Characterized by an empty circle (a single point missing).
- Typically occur in rational functions with factored common terms.

**Jump Discontinuities**

- Limit from left does not equal limit from right.
- Visualized by a vertical jump in the graph.

**Asymptote Discontinuities**

- Function values go to infinity.
- Represented by lines rushing towards but never touching a certain point.

Remember, identifying discontinuities requires practice. Keep drawing, keep watching, and soon, detecting these quirks will be second nature. Happy graphing, and may your functions be ever continuous—or deliciously discontinuous! 🍀🚀

#### Key Terms to Review

**Discontinuities:**Points where the graph breaks or has interruptions, causing values to be undefined or non-existent.**Removable Discontinuity:**A hole in the graph where the limit exists.**Jump Discontinuity:**An abrupt change where pieces of the graph don’t connect.**Step function:**A piecewise function resembling staircase steps, often leading to jump discontinuities.

### Final Thought

So, there we have it, navigators of numbers! 🎢🎓 Discontinuities might seem like bumps in the road, but with a bit of practice, you'll glide over them with ease. Now go forth and embrace the mathematical drama. And remember, a discontinuity is just a function's way of saying it likes to keep things interesting!