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  1. AP Calculus
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What are the differences between removable and non-removable discontinuities?

Removable: can be 'fixed' by redefining the function. Non-removable: cannot be fixed; often vertical asymptotes.

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What are the differences between removable and non-removable discontinuities?

Removable: can be 'fixed' by redefining the function. Non-removable: cannot be fixed; often vertical asymptotes.

Compare and contrast lim⁡x→a+f(x)=∞\lim_{x\to a^+} f(x) = \inftylimx→a+​f(x)=∞ and lim⁡x→a−f(x)=∞\lim_{x\to a^-} f(x) = \inftylimx→a−​f(x)=∞.

Both indicate the function approaches infinity, but the first approaches from the right, the second from the left.

Compare and contrast lim⁡x→a+f(x)=∞\lim_{x\to a^+} f(x) = \inftylimx→a+​f(x)=∞ and lim⁡x→a−f(x)=−∞\lim_{x\to a^-} f(x) = -\inftylimx→a−​f(x)=−∞.

The first approaches positive infinity from the right, the second approaches negative infinity from the left, indicating a vertical asymptote.

What is the difference between a limit existing and a vertical asymptote existing?

A limit exists if the function approaches a finite value. A vertical asymptote exists if the function approaches infinity.

Compare the behavior of a function near a vertical asymptote to its behavior near a hole (removable discontinuity).

Near a vertical asymptote, the function approaches infinity. Near a hole, the function approaches a finite value, but is undefined at that point.

Compare the graphs of f(x)=1xf(x) = \frac{1}{x}f(x)=x1​ and g(x)=1x2g(x) = \frac{1}{x^2}g(x)=x21​ near x=0.

f(x) has different signs on either side of x=0. g(x) is always positive.

Compare the domains of f(x)=ln⁡(x)f(x) = \ln(x)f(x)=ln(x) and g(x)=1xg(x) = \frac{1}{x}g(x)=x1​.

f(x) is defined for x > 0. g(x) is defined for all x except x = 0.

Contrast the behavior of polynomial functions with rational functions in terms of vertical asymptotes.

Polynomial functions do not have vertical asymptotes, while rational functions can have vertical asymptotes where the denominator is zero.

Compare the limits of f(x)=1x−af(x) = \frac{1}{x-a}f(x)=x−a1​ and g(x)=x−ag(x) = x-ag(x)=x−a as x approaches a.

The limit of f(x) is infinite, indicating a vertical asymptote. The limit of g(x) is 0.

Contrast the behavior of a function at a vertical asymptote where the power of the factor in the denominator is even versus odd.

Even power: function approaches same infinity from both sides. Odd power: function approaches opposite infinities from each side.

How to find vertical asymptotes of a rational function?

  1. Factor numerator and denominator. 2. Simplify the function. 3. Find values where the denominator is zero and the numerator is non-zero.

How to show x=ax=ax=a is a vertical asymptote using limits?

  1. Evaluate lim⁡x→a+f(x)\lim_{x\to a^+} f(x)limx→a+​f(x). 2. Evaluate lim⁡x→a−f(x)\lim_{x\to a^-} f(x)limx→a−​f(x). 3. Show that at least one of these limits is ±∞\pm \infty±∞.

How to determine if a discontinuity is removable or a vertical asymptote?

  1. Factor and simplify the function. 2. If a factor cancels, it's a removable discontinuity. 3. If a factor remains in the denominator, it's a vertical asymptote.

How to find the vertical asymptotes of f(x)=x+2x2−4f(x) = \frac{x+2}{x^2 - 4}f(x)=x2−4x+2​?

  1. Factor: f(x)=x+2(x+2)(x−2)f(x) = \frac{x+2}{(x+2)(x-2)}f(x)=(x+2)(x−2)x+2​. 2. Simplify: f(x)=1x−2f(x) = \frac{1}{x-2}f(x)=x−21​. 3. VA at x=2x=2x=2.

Steps to find vertical asymptotes of f(x)=tan⁡(x)f(x) = \tan(x)f(x)=tan(x)?

  1. Rewrite as f(x)=sin⁡(x)cos⁡(x)f(x) = \frac{\sin(x)}{\cos(x)}f(x)=cos(x)sin(x)​. 2. Find where cos⁡(x)=0\cos(x) = 0cos(x)=0. 3. x=(2n+1)π2x = \frac{(2n+1)\pi}{2}x=2(2n+1)π​, where n is an integer.

How to find the vertical asymptotes of f(x)=x2−1x−1f(x) = \frac{x^2 - 1}{x-1}f(x)=x−1x2−1​?

  1. Factor: f(x)=(x−1)(x+1)x−1f(x) = \frac{(x-1)(x+1)}{x-1}f(x)=x−1(x−1)(x+1)​. 2. Simplify: f(x)=x+1f(x) = x+1f(x)=x+1. 3. Removable discontinuity at x=1, no vertical asymptote.

How to find the limit of a rational function as x approaches a vertical asymptote?

  1. Determine the sign of the function as x approaches from the left and right. 2. The limit will be either positive or negative infinity.

How to solve for vertical asymptotes of f(x)=1x2+1f(x) = \frac{1}{x^2 + 1}f(x)=x2+11​?

  1. Set denominator equal to zero: x2+1=0x^2 + 1 = 0x2+1=0. 2. Solve for x: x2=−1x^2 = -1x2=−1. 3. No real solutions, so no vertical asymptotes.

How to find vertical asymptotes of f(x)=exxf(x) = \frac{e^x}{x}f(x)=xex​?

  1. Check where the denominator is zero: x=0x=0x=0. 2. Verify the numerator is not zero at x=0x=0x=0: e0=1≠0e^0 = 1 \neq 0e0=1=0. 3. Vertical asymptote at x=0x=0x=0.

How to determine the behavior of f(x)=1x−2f(x) = \frac{1}{x-2}f(x)=x−21​ as x approaches 2?

  1. Check limit from the right: lim⁡x→2+1x−2=∞\lim_{x\to 2^+} \frac{1}{x-2} = \inftylimx→2+​x−21​=∞. 2. Check limit from the left: lim⁡x→2−1x−2=−∞\lim_{x\to 2^-} \frac{1}{x-2} = -\inftylimx→2−​x−21​=−∞. 3. Vertical asymptote at x=2x=2x=2.

What does a vertical asymptote on the graph of f(x)f(x)f(x) indicate about f′(x)f'(x)f′(x)?

It suggests that f′(x)f'(x)f′(x) may also have a vertical asymptote or be unbounded near that x-value.

How can you identify a vertical asymptote from a graph?

Look for a vertical line that the function approaches but never crosses; the function's value tends towards ±∞\pm \infty±∞ near this line.

What does the graph of f(x)=1xf(x) = \frac{1}{x}f(x)=x1​ tell us about its limits near x=0x=0x=0?

It shows that lim⁡x→0+f(x)=∞\lim_{x\to 0^+} f(x) = \inftylimx→0+​f(x)=∞ and lim⁡x→0−f(x)=−∞\lim_{x\to 0^-} f(x) = -\inftylimx→0−​f(x)=−∞, indicating a vertical asymptote at x=0x=0x=0.

How does the graph of ln(x)ln(x)ln(x) confirm its vertical asymptote?

The graph approaches the y-axis (x=0x=0x=0) very closely as xxx approaches 0 from the right, and the function's value goes to negative infinity.

How can you determine the sign of the infinite limit from a graph near a vertical asymptote?

If the graph goes up towards the asymptote, the limit is positive infinity; if it goes down, the limit is negative infinity.

If a graph has a vertical asymptote at x=a, what does that imply about the domain of the function?

The function is not defined at x=a, so x=a is not in the domain.

How does the steepness of a graph near a vertical asymptote relate to the limit?

The steeper the graph gets as it approaches the asymptote, the faster the function is approaching infinity (either positive or negative).

What graphical feature indicates a removable discontinuity rather than a vertical asymptote?

A hole in the graph, indicating a point where the function is undefined but could be defined to make the function continuous.

How can you graphically distinguish between lim⁡x→a+f(x)=∞\lim_{x\to a^+} f(x) = \inftylimx→a+​f(x)=∞ and lim⁡x→a−f(x)=∞\lim_{x\to a^-} f(x) = \inftylimx→a−​f(x)=∞?

Both limits indicate the graph goes up near x=a. The first approaches from the right, the second from the left.

What does the graph of a function with a vertical asymptote at x=a look like near that point?

The graph will approach the vertical line x=a very closely, with the y-values either increasing or decreasing without bound.