AP Precalculus Flashcards: Rational Functions And Zeros

Study Rational Functions And Zeros in AP Precalculus with focused flashcards that help you recognize the idea, recall the key rule, and apply it in practice-style prompts.

AP Precalculus

Rational Functions And Zeros

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QUESTION
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Identify a removable discontinuity in f(x)=x21x1f(x) = \frac{x^2 - 1}{x - 1}.

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ANSWER

Removable discontinuity at x=1x = 1. The factor (x1)(x-1) cancels from numerator and denominator.

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What this deck covers

This deck focuses on Rational Functions And Zeros, giving you a quick way to review the definitions, rules, and examples that matter most for AP Precalculus.

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Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

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Flashcard 1: Identify a removable discontinuity in f(x)=x21x1f(x) = \frac{x^2 - 1}{x - 1}.

Answer: Removable discontinuity at x=1x = 1. The factor (x1)(x-1) cancels from numerator and denominator.

Flashcard 2: How do you determine a hole in a rational function?

Answer: If p(x)p(x) and q(x)q(x) share a common factor. Common factors can be cancelled, creating a removable discontinuity.

Flashcard 3: Identify the hole in f(x)=x21x1f(x) = \frac{x^2 - 1}{x - 1}.

Answer: Hole at x=1x = 1. Factor x21=(x1)(x+1)x^2 - 1 = (x-1)(x+1) and cancel the common factor.

Flashcard 4: What is a zero of a rational function?

Answer: A value of xx for which f(x)=0f(x) = 0. A zero occurs when the numerator equals zero but the denominator doesn't.

Flashcard 5: What is the behavior of f(x)=2xx+5f(x) = \frac{2x}{x + 5} as x5x \to -5?

Answer: As x5x \to -5, f(x)±f(x) \to \pm \infty. The function has a vertical asymptote at x=5x = -5.

Flashcard 6: What is the slant asymptote of f(x)=x2+1xf(x) = \frac{x^2 + 1}{x}?

Answer: The slant asymptote is y=xy = x. Divide x2+1x^2 + 1 by xx using polynomial long division.

Flashcard 7: What is the horizontal asymptote of f(x)=7x2x+3f(x) = \frac{7x}{2x + 3}?

Answer: The horizontal asymptote is y=72y = \frac{7}{2}. Equal degrees give horizontal asymptote y=72y = \frac{7}{2}.

Flashcard 8: Identify the hole in f(x)=x21x1f(x) = \frac{x^2 - 1}{x - 1}.

Answer: Hole at x=1x = 1. Factor x21=(x1)(x+1)x^2 - 1 = (x-1)(x+1) and cancel the common factor.

Flashcard 9: Find the zeros of f(x)=3x212x+2f(x) = \frac{3x^2 - 12}{x + 2}.

Answer: The zeros are x=2x = 2 and x=2x = -2. Factor the numerator: 3x212=3(x24)=3(x2)(x+2)3x^2 - 12 = 3(x^2 - 4) = 3(x-2)(x+2).

Flashcard 10: What is the horizontal asymptote of f(x)=7x2x+3f(x) = \frac{7x}{2x + 3}?

Answer: The horizontal asymptote is y=72y = \frac{7}{2}. Equal degrees give horizontal asymptote y=72y = \frac{7}{2}.

Flashcard 11: What is a zero of a rational function?

Answer: A value of xx for which f(x)=0f(x) = 0. A zero occurs when the numerator equals zero but the denominator doesn't.

Flashcard 12: What is the degree of the polynomial p(x)=3x42x2+1p(x) = 3x^4 - 2x^2 + 1?

Answer: The degree is 4. The highest power term determines the degree of a polynomial.

Flashcard 13: Find the vertical asymptote of f(x)=2x+3x4f(x) = \frac{2x + 3}{x - 4}.

Answer: Vertical asymptote at x=4x = 4. Set the denominator x4=0x - 4 = 0 to find the vertical asymptote.

Flashcard 14: Identify the vertical asymptote of f(x)=2xx24f(x) = \frac{2x}{x^2 - 4}.

Answer: Vertical asymptotes are x=2x = 2 and x=2x = -2. Factor x24=(x2)(x+2)x^2 - 4 = (x-2)(x+2) to find where the denominator is zero.

Flashcard 15: What are the zeros of f(x)=x29x+2f(x) = \frac{x^2 - 9}{x + 2}?

Answer: The zeros are x=3x = 3 and x=3x = -3. Factor the numerator: x29=(x3)(x+3)x^2 - 9 = (x-3)(x+3).

Flashcard 16: Find the vertical asymptote of f(x)=2x+3x4f(x) = \frac{2x + 3}{x - 4}.

Answer: Vertical asymptote at x=4x = 4. Set the denominator x4=0x - 4 = 0 to find the vertical asymptote.

Flashcard 17: What is the behavior of f(x)=1xf(x) = \frac{1}{x} as x0x \to 0?

Answer: As x0x \to 0, f(x)±f(x) \to \pm \infty. The function has a vertical asymptote at x=0x = 0.

Flashcard 18: What is the degree of q(x)=x37xq(x) = x^3 - 7x?

Answer: The degree is 3. The highest power term x3x^3 has degree 3.

Flashcard 19: What is the behavior of f(x)=xx21f(x) = \frac{x}{x^2 - 1} as x1x \to 1?

Answer: As x1x \to 1, f(x)f(x) \to \infty. The denominator (x1)(x-1) approaches 0 while numerator approaches 1.

Flashcard 20: What is the horizontal asymptote for f(x)=x+1x+2f(x) = \frac{x + 1}{x + 2}?

Answer: The horizontal asymptote is y=1y = 1. When degrees are equal, the horizontal asymptote is 11=1\frac{1}{1} = 1.

Flashcard 21: Identify a removable discontinuity in f(x)=x21x1f(x) = \frac{x^2 - 1}{x - 1}.

Answer: Removable discontinuity at x=1x = 1. The factor (x1)(x-1) cancels from numerator and denominator.

Flashcard 22: What is the horizontal asymptote for f(x)=2x2x2+1f(x) = \frac{2x^2}{x^2 + 1}?

Answer: The horizontal asymptote is y=2y = 2. Equal degrees give horizontal asymptote y=21=2y = \frac{2}{1} = 2.

Flashcard 23: Which term denotes values not in the domain of a rational function?

Answer: These are the poles or vertical asymptotes. Points where the denominator equals zero make the function undefined.

Flashcard 24: State the horizontal asymptote for f(x)=4xx+2f(x) = \frac{4x}{x + 2}.

Answer: The horizontal asymptote is y=4y = 4. As xx \to \infty, the function approaches 41=4\frac{4}{1} = 4.

Flashcard 25: What is the domain of f(x)=xx24xf(x) = \frac{x}{x^2 - 4x}?

Answer: Domain: x0,x4x \neq 0, x \neq 4. Factor the denominator: x24x=x(x4)x^2 - 4x = x(x - 4).

Flashcard 26: Identify the horizontal asymptote of f(x)=x2+3x21f(x) = \frac{x^2 + 3}{x^2 - 1}.

Answer: The horizontal asymptote is y=1y = 1. When degrees are equal, the horizontal asymptote equals the ratio of leading coefficients.

Flashcard 27: Identify the horizontal asymptote of f(x)=5xx2+4f(x) = \frac{5x}{x^2 + 4}.

Answer: The horizontal asymptote is y=0y = 0. Numerator degree is less than denominator degree, so y=0y = 0.

Flashcard 28: What is the behavior of f(x)=xx21f(x) = \frac{x}{x^2 - 1} as x1x \to 1?

Answer: As x1x \to 1, f(x)f(x) \to \infty. The denominator (x1)(x-1) approaches 0 while numerator approaches 1.

Flashcard 29: State the horizontal asymptote of f(x)=2x2+3x2+1f(x) = \frac{2x^2 + 3}{x^2 + 1}.

Answer: The horizontal asymptote is y=2y = 2. Equal degrees give horizontal asymptote y=21=2y = \frac{2}{1} = 2.

Flashcard 30: What are the zeros of f(x)=x29x+2f(x) = \frac{x^2 - 9}{x + 2}?

Answer: The zeros are x=3x = 3 and x=3x = -3. Factor the numerator: x29=(x3)(x+3)x^2 - 9 = (x-3)(x+3).

Flashcard 31: State the condition for a vertical asymptote in a rational function.

Answer: Occurs where q(x)=0q(x) = 0 and p(x)0p(x) \neq 0. The denominator is zero while the numerator is non-zero.

Flashcard 32: What is the behavior of f(x)=1xf(x) = \frac{1}{x} as x0x \to 0?

Answer: As x0x \to 0, f(x)±f(x) \to \pm \infty. The function has a vertical asymptote at x=0x = 0.

Flashcard 33: Which term describes xx values making f(x)f(x) undefined?

Answer: These are the excluded values or domain restrictions. Values that make the denominator zero are excluded from the domain.

Flashcard 34: Which term describes xx values making f(x)f(x) undefined?

Answer: These are the excluded values or domain restrictions. Values that make the denominator zero are excluded from the domain.

Flashcard 35: Find the zero of f(x)=2x4x+3f(x) = \frac{2x - 4}{x + 3}.

Answer: The zero is x=2x = 2. Set 2x4=02x - 4 = 0 to find where the numerator equals zero.

Flashcard 36: Find the domain of f(x)=4x+1x29f(x) = \frac{4x + 1}{x^2 - 9}.

Answer: Domain: x3,x3x \neq 3, x \neq -3. Set x29=0x^2 - 9 = 0 to find where the function is undefined.

Flashcard 37: Identify the horizontal asymptote of f(x)=5xx2+4f(x) = \frac{5x}{x^2 + 4}.

Answer: The horizontal asymptote is y=0y = 0. Numerator degree is less than denominator degree, so y=0y = 0.

Flashcard 38: Which term denotes values not in the domain of a rational function?

Answer: These are the poles or vertical asymptotes. Points where the denominator equals zero make the function undefined.

Flashcard 39: What is the degree of q(x)=x37xq(x) = x^3 - 7x?

Answer: The degree is 3. The highest power term x3x^3 has degree 3.

Flashcard 40: What is the horizontal asymptote for f(x)=x+1x+2f(x) = \frac{x + 1}{x + 2}?

Answer: The horizontal asymptote is y=1y = 1. When degrees are equal, the horizontal asymptote is 11=1\frac{1}{1} = 1.

Flashcard 41: Identify the vertical asymptote of f(x)=5x225f(x) = \frac{5}{x^2 - 25}.

Answer: Vertical asymptotes at x=5x = 5 and x=5x = -5. Factor the denominator: x225=(x5)(x+5)x^2 - 25 = (x-5)(x+5).

Flashcard 42: Find the zeros of f(x)=3x212x+2f(x) = \frac{3x^2 - 12}{x + 2}.

Answer: The zeros are x=2x = 2 and x=2x = -2. Factor the numerator: 3x212=3(x24)=3(x2)(x+2)3x^2 - 12 = 3(x^2 - 4) = 3(x-2)(x+2).

Flashcard 43: What is the domain of f(x)=xx24xf(x) = \frac{x}{x^2 - 4x}?

Answer: Domain: x0,x4x \neq 0, x \neq 4. Factor the denominator: x24x=x(x4)x^2 - 4x = x(x - 4).

Flashcard 44: State the horizontal asymptote of f(x)=2x2+3x2+1f(x) = \frac{2x^2 + 3}{x^2 + 1}.

Answer: The horizontal asymptote is y=2y = 2. Equal degrees give horizontal asymptote y=21=2y = \frac{2}{1} = 2.

Flashcard 45: State the condition for a vertical asymptote in a rational function.

Answer: Occurs where q(x)=0q(x) = 0 and p(x)0p(x) \neq 0. The denominator is zero while the numerator is non-zero.

Flashcard 46: Find the zero of f(x)=x4x+1f(x) = \frac{x - 4}{x + 1}.

Answer: The zero is x=4x = 4. Set the numerator x4=0x - 4 = 0 to find where f(x)=0f(x) = 0.

Flashcard 47: For f(x)=x24x2f(x) = \frac{x^2 - 4}{x - 2}, what is the discontinuity?

Answer: Discontinuity (hole) at x=2x = 2. Factor and cancel: (x2)(x-2) appears in both numerator and denominator.

Flashcard 48: Find the domain of f(x)=4x+1x29f(x) = \frac{4x + 1}{x^2 - 9}.

Answer: Domain: x3,x3x \neq 3, x \neq -3. Set x29=0x^2 - 9 = 0 to find where the function is undefined.

Flashcard 49: State the vertical asymptote of f(x)=2x+1x216f(x) = \frac{2x + 1}{x^2 - 16}.

Answer: Vertical asymptotes at x=4x = 4 and x=4x = -4. Factor the denominator: x216=(x4)(x+4)x^2 - 16 = (x-4)(x+4).

Flashcard 50: Identify the horizontal asymptote of f(x)=x2+3x21f(x) = \frac{x^2 + 3}{x^2 - 1}.

Answer: The horizontal asymptote is y=1y = 1. When degrees are equal, the horizontal asymptote equals the ratio of leading coefficients.

Flashcard 51: What is the domain of f(x)=1x(x+3)f(x) = \frac{1}{x(x + 3)}?

Answer: Domain: x0,x3x \neq 0, x \neq -3. Set x(x+3)=0x(x + 3) = 0 to find where the function is undefined.

Flashcard 52: What is the end behavior of f(x)=3x3+45x3+2f(x) = \frac{3x^3 + 4}{5x^3 + 2}?

Answer: As x±x \to \pm \infty, f(x)35f(x) \to \frac{3}{5}. When degrees are equal, divide leading coefficients: 35\frac{3}{5}.

Flashcard 53: What is the behavior of f(x)=2xx+5f(x) = \frac{2x}{x + 5} as x5x \to -5?

Answer: As x5x \to -5, f(x)±f(x) \to \pm \infty. The function has a vertical asymptote at x=5x = -5.

Flashcard 54: Identify the vertical asymptote of f(x)=5x225f(x) = \frac{5}{x^2 - 25}.

Answer: Vertical asymptotes at x=5x = 5 and x=5x = -5. Factor the denominator: x225=(x5)(x+5)x^2 - 25 = (x-5)(x+5).

Flashcard 55: For f(x)=x24x2f(x) = \frac{x^2 - 4}{x - 2}, what is the discontinuity?

Answer: Discontinuity (hole) at x=2x = 2. Factor and cancel: (x2)(x-2) appears in both numerator and denominator.

Flashcard 56: What is the intercept of f(x)=3x2f(x) = \frac{3}{x-2}?

Answer: Vertical intercept at (0,32)(0, -\frac{3}{2}). Substitute x=0x = 0 into the function to find the y-intercept.

Flashcard 57: What is the horizontal asymptote for f(x)=2x2x2+1f(x) = \frac{2x^2}{x^2 + 1}?

Answer: The horizontal asymptote is y=2y = 2. Equal degrees give horizontal asymptote y=21=2y = \frac{2}{1} = 2.

Flashcard 58: Describe when a rational function has no horizontal asymptote.

Answer: When the degree of p(x)p(x) is greater than q(x)q(x). When numerator degree exceeds denominator degree, no horizontal asymptote exists.

Flashcard 59: How do you determine a hole in a rational function?

Answer: If p(x)p(x) and q(x)q(x) share a common factor. Common factors can be cancelled, creating a removable discontinuity.

Flashcard 60: Find the zero of f(x)=2x4x+3f(x) = \frac{2x - 4}{x + 3}.

Answer: The zero is x=2x = 2. Set 2x4=02x - 4 = 0 to find where the numerator equals zero.

Flashcard 61: Describe when a rational function has no horizontal asymptote.

Answer: When the degree of p(x)p(x) is greater than q(x)q(x). When numerator degree exceeds denominator degree, no horizontal asymptote exists.

Flashcard 62: What is the degree of the polynomial p(x)=3x42x2+1p(x) = 3x^4 - 2x^2 + 1?

Answer: The degree is 4. The highest power term determines the degree of a polynomial.

Flashcard 63: What happens to f(x)=1x3f(x) = \frac{1}{x-3} as x3x \to 3?

Answer: f(x)±f(x) \to \pm \infty, vertical asymptote at x=3x = 3. As xx approaches 3, the denominator approaches 0 while numerator stays 1.

Flashcard 64: What is the general form of a rational function?

Answer: f(x)=p(x)q(x)f(x) = \frac{p(x)}{q(x)} where p(x)p(x) and q(x)q(x) are polynomials. This defines a rational function as a ratio of two polynomial functions.

Flashcard 65: State the vertical asymptote of f(x)=2x+1x216f(x) = \frac{2x + 1}{x^2 - 16}.

Answer: Vertical asymptotes at x=4x = 4 and x=4x = -4. Factor the denominator: x216=(x4)(x+4)x^2 - 16 = (x-4)(x+4).

Flashcard 66: What is the slant asymptote of f(x)=x2+1xf(x) = \frac{x^2 + 1}{x}?

Answer: The slant asymptote is y=xy = x. Divide x2+1x^2 + 1 by xx using polynomial long division.

Flashcard 67: State the horizontal asymptote for f(x)=4xx+2f(x) = \frac{4x}{x + 2}.

Answer: The horizontal asymptote is y=4y = 4. As xx \to \infty, the function approaches 41=4\frac{4}{1} = 4.

Flashcard 68: What is the y-intercept of f(x)=2x5x+3f(x) = \frac{2x - 5}{x + 3}?

Answer: The y-intercept is (0,53)(0, -\frac{5}{3}). Substitute x=0x = 0 to get f(0)=53f(0) = \frac{-5}{3}.

Flashcard 69: Find the zero of f(x)=x4x+1f(x) = \frac{x - 4}{x + 1}.

Answer: The zero is x=4x = 4. Set the numerator x4=0x - 4 = 0 to find where f(x)=0f(x) = 0.

Flashcard 70: What is the domain of f(x)=1x(x+3)f(x) = \frac{1}{x(x + 3)}?

Answer: Domain: x0,x3x \neq 0, x \neq -3. Set x(x+3)=0x(x + 3) = 0 to find where the function is undefined.

Flashcard 71: What happens to f(x)=1x3f(x) = \frac{1}{x-3} as x3x \to 3?

Answer: f(x)±f(x) \to \pm \infty, vertical asymptote at x=3x = 3. As xx approaches 3, the denominator approaches 0 while numerator stays 1.

Flashcard 72: What is the general form of a rational function?

Answer: f(x)=p(x)q(x)f(x) = \frac{p(x)}{q(x)} where p(x)p(x) and q(x)q(x) are polynomials. This defines a rational function as a ratio of two polynomial functions.