AP Calculus BC Flashcards: Second Derivative Test

Study Second Derivative Test in AP Calculus BC with focused flashcards that help you recognize the idea, recall the key rule, and apply it in practice-style prompts.

AP Calculus BC

Second Derivative Test

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QUESTION
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Evaluate f(2)f''(2) for f(x)=x44x3+6x2f(x) = x^4 - 4x^3 + 6x^2.

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ANSWER

f(2)=12f''(2) = 12. f(x)=4x312x2+12xf'(x) = 4x^3 - 12x^2 + 12x, so f(x)=12x224x+12f''(x) = 12x^2 - 24x + 12.

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Flashcard 1: Evaluate f(2)f''(2) for f(x)=x44x3+6x2f(x) = x^4 - 4x^3 + 6x^2.

Answer: f(2)=12f''(2) = 12. f(x)=4x312x2+12xf'(x) = 4x^3 - 12x^2 + 12x, so f(x)=12x224x+12f''(x) = 12x^2 - 24x + 12.

Flashcard 2: Evaluate f(0)f''(0) for f(x)=x44x2+1f(x) = x^4 - 4x^2 + 1.

Answer: f(0)=8f''(0) = -8. f(x)=4x38xf'(x) = 4x^3 - 8x, so f(x)=12x28f''(x) = 12x^2 - 8 and f(0)=8f''(0) = -8.

Flashcard 3: What is the second derivative of f(x)=x4+2x2xf(x) = -x^4 + 2x^2 - x?

Answer: f(x)=12x2+4f''(x) = -12x^2 + 4. Differentiate f(x)=4x3+4x1f'(x) = -4x^3 + 4x - 1 to get the second derivative.

Flashcard 4: What is the sign of f(x)f''(x) if f(x)f(x) is concave down?

Answer: Negative. Concave down functions have negative curvature everywhere.

Flashcard 5: What does f(c)<0f''(c) < 0 imply about f(x)f(x) at x=cx=c?

Answer: Local maximum. Negative second derivative confirms the critical point is a maximum.

Flashcard 6: What is the sign of f(x)f''(x) if f(x)f(x) is concave up?

Answer: Positive. Concave up functions have positive curvature everywhere.

Flashcard 7: What is the second derivative of f(x)=3x48x2+5f(x) = 3x^4 - 8x^2 + 5?

Answer: f(x)=36x216f''(x) = 36x^2 - 16. Differentiate f(x)=12x316xf'(x) = 12x^3 - 16x to get the second derivative.

Flashcard 8: What does f(c)=0f''(c) = 0 indicate about the critical point cc?

Answer: Test is inconclusive at cc. Zero second derivative provides no information about the extremum type.

Flashcard 9: Find the second derivative of f(x)=x3+3x2+x+1f(x) = x^3 + 3x^2 + x + 1.

Answer: f(x)=6x+6f''(x) = 6x + 6. Differentiate f(x)=3x2+6x+1f'(x) = 3x^2 + 6x + 1 to get the second derivative.

Flashcard 10: Determine the nature of the extremum at x=12x = \frac{1}{2} for f(x)=x2+xf(x) = -x^2 + x.

Answer: Local maximum. f(1/2)=2<0f''(1/2) = -2 < 0 at the critical point, indicating a maximum.

Flashcard 11: Determine if f(x)=x33x2+4f(x) = x^3 - 3x^2 + 4 has a local extremum at x=2x = 2.

Answer: Local minimum at x=2x = 2. f(2)=0f'(2) = 0 and f(2)=6>0f''(2) = 6 > 0, confirming a local minimum.

Flashcard 12: What does f(c)>0f''(c) > 0 imply about f(x)f(x) at x=cx=c?

Answer: Local minimum. Positive second derivative confirms the critical point is a minimum.

Flashcard 13: What does f(c)>0f''(c) > 0 imply about f(x)f(x) at x=cx=c?

Answer: Local minimum. Positive second derivative confirms the critical point is a minimum.

Flashcard 14: Evaluate f(1)f''(1) for f(x)=x4x2+xf(x) = x^4 - x^2 + x.

Answer: f(1)=10f''(1) = 10. f(x)=4x32x+1f'(x) = 4x^3 - 2x + 1 and f(x)=12x22f''(x) = 12x^2 - 2, so f(1)=10f''(1) = 10.

Flashcard 15: Find the second derivative of f(x)=x55x3+7f(x) = x^5 - 5x^3 + 7.

Answer: f(x)=20x330xf''(x) = 20x^3 - 30x. Differentiate f(x)=5x415x2f'(x) = 5x^4 - 15x^2 to get the second derivative.

Flashcard 16: State the second derivative test condition for a local maximum.

Answer: f(c)<0f''(c) < 0 at critical point cc. Negative second derivative indicates concave down, confirming a maximum.

Flashcard 17: Determine the nature of the extremum for f(x)=x24x+4f(x) = x^2 - 4x + 4 at x=2x = 2.

Answer: Local minimum. f(2)=0f'(2) = 0 and f(2)=2>0f''(2) = 2 > 0, confirming a local minimum.

Flashcard 18: What does f(c)<0f''(c) < 0 imply about f(x)f(x) at x=cx=c?

Answer: Local maximum. Negative second derivative confirms the critical point is a maximum.

Flashcard 19: Identify the nature of the critical point for f(x)=x33xf(x) = x^3 - 3x at x=0x = 0.

Answer: Inconclusive. f(0)=0f''(0) = 0 at this critical point, so the test fails.

Flashcard 20: At which type of point is the second derivative test applied?

Answer: Critical points. Only points where f(x)=0f'(x) = 0 can be tested for extrema.

Flashcard 21: What is the sign of f(x)f''(x) if f(x)f(x) is concave down?

Answer: Negative. Concave down functions have negative curvature everywhere.

Flashcard 22: Find f(x)f''(x) for f(x)=x44x2+2f(x) = x^4 - 4x^2 + 2.

Answer: f(x)=12x28f''(x) = 12x^2 - 8. Take the derivative of f(x)=4x38xf'(x) = 4x^3 - 8x to get the second derivative.

Flashcard 23: What is the second derivative of f(x)=x3+3x5f(x) = -x^3 + 3x - 5?

Answer: f(x)=6xf''(x) = -6x. Differentiate f(x)=3x2+3f'(x) = -3x^2 + 3 to get the second derivative.

Flashcard 24: Calculate f(3)f''(3) for f(x)=x39x2+27x3f(x) = x^3 - 9x^2 + 27x - 3.

Answer: f(3)=0f''(3) = 0. f(x)=3x218x+27f'(x) = 3x^2 - 18x + 27 and f(x)=6x18f''(x) = 6x - 18, so f(3)=0f''(3) = 0.

Flashcard 25: What is the second derivative test used for?

Answer: Determining local extrema of a function. Uses concavity at critical points to classify local maxima and minima.

Flashcard 26: Determine the nature of the extremum for f(x)=x24x+4f(x) = x^2 - 4x + 4 at x=2x = 2.

Answer: Local minimum. f(2)=0f'(2) = 0 and f(2)=2>0f''(2) = 2 > 0, confirming a local minimum.

Flashcard 27: What conclusion is drawn if f(c)=0f''(c) = 0 at a critical point cc?

Answer: Test inconclusive. Zero second derivative means the test cannot determine extremum type.

Flashcard 28: Identify the sign of f(x)f''(x) for a concave up interval.

Answer: f(x)>0f''(x) > 0. Positive second derivative always indicates upward concavity.

Flashcard 29: Find the second derivative of f(x)=13x32x2+3xf(x) = \frac{1}{3}x^3 - 2x^2 + 3x.

Answer: f(x)=2x4f''(x) = 2x - 4. f(x)=x24x+3f'(x) = x^2 - 4x + 3, so f(x)=2x4f''(x) = 2x - 4.

Flashcard 30: What is the second derivative of f(x)=2x33x2+xf(x) = 2x^3 - 3x^2 + x?

Answer: f(x)=12x6f''(x) = 12x - 6. Differentiate f(x)=6x26x+1f'(x) = 6x^2 - 6x + 1 to get the second derivative.

Flashcard 31: Calculate f(3)f''(3) for f(x)=x39x2+27x3f(x) = x^3 - 9x^2 + 27x - 3.

Answer: f(3)=0f''(3) = 0. f(x)=3x218x+27f'(x) = 3x^2 - 18x + 27 and f(x)=6x18f''(x) = 6x - 18, so f(3)=0f''(3) = 0.

Flashcard 32: What conclusion is drawn if f(c)=0f''(c) = 0 at a critical point cc?

Answer: Test inconclusive. Zero second derivative means the test cannot determine extremum type.

Flashcard 33: Identify the sign of f(x)f''(x) for a concave down interval.

Answer: f(x)<0f''(x) < 0. Negative second derivative always indicates downward concavity.

Flashcard 34: Identify the sign of f(x)f''(x) for a concave up interval.

Answer: f(x)>0f''(x) > 0. Positive second derivative always indicates upward concavity.

Flashcard 35: Find the second derivative of f(x)=13x32x2+3xf(x) = \frac{1}{3}x^3 - 2x^2 + 3x.

Answer: f(x)=2x4f''(x) = 2x - 4. f(x)=x24x+3f'(x) = x^2 - 4x + 3, so f(x)=2x4f''(x) = 2x - 4.

Flashcard 36: Find f(x)f''(x) for f(x)=x44x2+2f(x) = x^4 - 4x^2 + 2.

Answer: f(x)=12x28f''(x) = 12x^2 - 8. Take the derivative of f(x)=4x38xf'(x) = 4x^3 - 8x to get the second derivative.

Flashcard 37: What is the second derivative of f(x)=3x48x2+5f(x) = 3x^4 - 8x^2 + 5?

Answer: f(x)=36x216f''(x) = 36x^2 - 16. Differentiate f(x)=12x316xf'(x) = 12x^3 - 16x to get the second derivative.

Flashcard 38: Determine the nature of the extremum for f(x)=x24f(x) = x^2 - 4 at x=0x = 0.

Answer: Local minimum. f(0)=0f'(0) = 0 and f(0)=2>0f''(0) = 2 > 0, confirming a local minimum.

Flashcard 39: What is the condition for test inconclusiveness in the second derivative test?

Answer: f(c)=0f''(c) = 0 at cc. This condition makes the second derivative test unable to determine extremum type.

Flashcard 40: What is the second derivative of f(x)=2x33x2+xf(x) = 2x^3 - 3x^2 + x?

Answer: f(x)=12x6f''(x) = 12x - 6. Differentiate f(x)=6x26x+1f'(x) = 6x^2 - 6x + 1 to get the second derivative.

Flashcard 41: What is the second derivative of f(x)=x3+3x5f(x) = -x^3 + 3x - 5?

Answer: f(x)=6xf''(x) = -6x. Differentiate f(x)=3x2+3f'(x) = -3x^2 + 3 to get the second derivative.

Flashcard 42: What is the sign of f(x)f''(x) if f(x)f(x) is concave up?

Answer: Positive. Concave up functions have positive curvature everywhere.

Flashcard 43: Find the second derivative of f(x)=x55x3+7f(x) = x^5 - 5x^3 + 7.

Answer: f(x)=20x330xf''(x) = 20x^3 - 30x. Differentiate f(x)=5x415x2f'(x) = 5x^4 - 15x^2 to get the second derivative.

Flashcard 44: State the second derivative test condition for a local minimum.

Answer: f(c)>0f''(c) > 0 at critical point cc. Positive second derivative indicates concave up, confirming a minimum.

Flashcard 45: What is the second derivative of f(x)=x4+2x2xf(x) = -x^4 + 2x^2 - x?

Answer: f(x)=12x2+4f''(x) = -12x^2 + 4. Differentiate f(x)=4x3+4x1f'(x) = -4x^3 + 4x - 1 to get the second derivative.

Flashcard 46: Determine concavity for f(x)=2x23x+1f(x) = 2x^2 - 3x + 1 at x=0x = 0.

Answer: Concave up. f(x)=4>0f''(x) = 4 > 0 everywhere, so the function is concave up.

Flashcard 47: Determine concavity for f(x)=2x23x+1f(x) = 2x^2 - 3x + 1 at x=0x = 0.

Answer: Concave up. f(x)=4>0f''(x) = 4 > 0 everywhere, so the function is concave up.

Flashcard 48: Evaluate f(0)f''(0) for f(x)=x44x2+1f(x) = x^4 - 4x^2 + 1.

Answer: f(0)=8f''(0) = -8. f(x)=4x38xf'(x) = 4x^3 - 8x, so f(x)=12x28f''(x) = 12x^2 - 8 and f(0)=8f''(0) = -8.

Flashcard 49: Determine the nature of the extremum for f(x)=x24f(x) = x^2 - 4 at x=0x = 0.

Answer: Local minimum. f(0)=0f'(0) = 0 and f(0)=2>0f''(0) = 2 > 0, confirming a local minimum.

Flashcard 50: At which type of point is the second derivative test applied?

Answer: Critical points. Only points where f(x)=0f'(x) = 0 can be tested for extrema.

Flashcard 51: What is the condition for test inconclusiveness in the second derivative test?

Answer: f(c)=0f''(c) = 0 at cc. This condition makes the second derivative test unable to determine extremum type.

Flashcard 52: What does f(c)=0f''(c) = 0 indicate about the critical point cc?

Answer: Test is inconclusive at cc. Zero second derivative provides no information about the extremum type.

Flashcard 53: Evaluate f(2)f''(2) for f(x)=x44x3+6x2f(x) = x^4 - 4x^3 + 6x^2.

Answer: f(2)=12f''(2) = 12. f(x)=4x312x2+12xf'(x) = 4x^3 - 12x^2 + 12x, so f(x)=12x224x+12f''(x) = 12x^2 - 24x + 12.

Flashcard 54: State the second derivative test condition for a local maximum.

Answer: f(c)<0f''(c) < 0 at critical point cc. Negative second derivative indicates concave down, confirming a maximum.

Flashcard 55: Determine the nature of the extremum at x=12x = \frac{1}{2} for f(x)=x2+xf(x) = -x^2 + x.

Answer: Local maximum. f(1/2)=2<0f''(1/2) = -2 < 0 at the critical point, indicating a maximum.

Flashcard 56: Find the second derivative of f(x)=x3+3x2+x+1f(x) = x^3 + 3x^2 + x + 1.

Answer: f(x)=6x+6f''(x) = 6x + 6. Differentiate f(x)=3x2+6x+1f'(x) = 3x^2 + 6x + 1 to get the second derivative.

Flashcard 57: Evaluate f(1)f''(1) for f(x)=x4x2+xf(x) = x^4 - x^2 + x.

Answer: f(1)=10f''(1) = 10. f(x)=4x32x+1f'(x) = 4x^3 - 2x + 1 and f(x)=12x22f''(x) = 12x^2 - 2, so f(1)=10f''(1) = 10.

Flashcard 58: Identify the nature of the critical point for f(x)=x33xf(x) = x^3 - 3x at x=0x = 0.

Answer: Inconclusive. f(0)=0f''(0) = 0 at this critical point, so the test fails.

Flashcard 59: State the second derivative test condition for a local minimum.

Answer: f(c)>0f''(c) > 0 at critical point cc. Positive second derivative indicates concave up, confirming a minimum.

Flashcard 60: Determine if f(x)=x33x2+4f(x) = x^3 - 3x^2 + 4 has a local extremum at x=2x = 2.

Answer: Local minimum at x=2x = 2. f(2)=0f'(2) = 0 and f(2)=6>0f''(2) = 6 > 0, confirming a local minimum.