All flashcards
Flashcard 1: What must be true of f(x) and g(x) in L'Hospital's Rule?
Answer: f(x) and g(x) must be differentiable near c. Functions must be differentiable for L'Hospital's Rule to work.
Flashcard 2: Find the limit: limx→0xtanx using L'Hospital's Rule.
Answer:
- Derivative of tanx is sec2x; 1sec20=1.
Flashcard 3: Define indeterminate form.
Answer: A form like 00 or ∞∞ where limits are not immediately obvious. Forms where direct evaluation is unclear or undefined.
Flashcard 4: Identify the indeterminate form: limx→0x21−cosx.
Answer: 00. Both 1−cos0=0 and 02=0 give 00.
Flashcard 5: What must the original limit be for L'Hospital's Rule to apply?
Answer: An indeterminate form. L'Hospital's Rule requires indeterminate forms to be valid.
Flashcard 6: Find the derivative of tanx for L'Hospital's Rule.
Answer: sec2x. Derivative of tangent function.
Flashcard 7: List a requirement for L'Hospital's Rule to be valid.
Answer: Both f(x) and g(x) must approach 0 or ∞ as x→c. Essential condition for applying the rule correctly.
Flashcard 8: Identify the indeterminate form: limx→∞x2+xx2.
Answer: ∞∞. Both numerator and denominator approach infinity.
Flashcard 9: Find the derivative of ex needed for L'Hospital's Rule.
Answer: ex. Basic exponential derivative.
Flashcard 10: Find the limit: limx→0sinxx2 using L'Hospital's Rule.
Answer:
- Apply L'Hospital's Rule: limx→0cosx2x=0.
Flashcard 11: Find the limit using L'Hospital's Rule: limx→0xex−1.
Answer:
- Derivative of ex−1 is ex; derivative of x is 1; 1e0=1.
Flashcard 12: What is the derivative of sinx needed for L'Hospital's Rule?
Answer: cosx. Basic trigonometric derivative.
Flashcard 13: Find the limit: limx→∞exx2 using L'Hospital's Rule.
Answer:
- Apply L'Hospital's Rule repeatedly; exponential grows faster than polynomial.
Flashcard 14: State L'Hospital's Rule for ∞∞ form.
Answer: limx→cg(x)f(x)=limx→cg′(x)f′(x) if ∞∞ form. Same rule applies for ∞∞ form.
Flashcard 15: What is L'Hospital's Rule used for?
Answer: Determining limits of indeterminate forms like 00 or ∞∞. Applies when direct substitution gives undefined ratios.
Flashcard 16: State L'Hospital's Rule for 00 form.
Answer: limx→cg(x)f(x)=limx→cg′(x)f′(x) if 00 form. Take derivatives of numerator and denominator separately.
Flashcard 17: Identify the indeterminate form: limx→0xsinx.
Answer: 00. Both sin0=0 and 0 in denominator give 00.
Flashcard 18: Find the limit: limx→0xln(1+x) using L'Hospital's Rule.
Answer:
- Derivative of ln(1+x) is 1+x1; 11+01=1.
Flashcard 19: Identify the indeterminate form: limx→∞exx.
Answer: ∞∞. Both x→∞ and ex→∞ give ∞∞.
Flashcard 20: Find the derivative of lnx for L'Hospital's Rule.
Answer: x1. Basic logarithmic derivative.
Flashcard 21: Find the limit: limx→1x−1x3−1 using L'Hospital's Rule.
Answer:
- Derivative of x3−1 is 3x2; derivative of x−1 is 1; 13(1)2=3.
Flashcard 22: Find the limit: limx→∞xln(x2) using L'Hospital's Rule.
Answer:
- Use chain rule: derivative of ln(x2) is x2; limit is 0.
Flashcard 23: Find the derivative of secx for L'Hospital's Rule.
Answer: secxtanx. Derivative of secant function.
Flashcard 24: Find the limit: limx→0x1−cosx using L'Hospital's Rule.
Answer:
- Derivative of 1−cosx is sinx; 1sin0=0.
Flashcard 25: Does L'Hospital's Rule apply to limx→0x1?
Answer: No, it's not an indeterminate form. The limit approaches ±∞, not an indeterminate form.
Flashcard 26: Find the derivative of cosx for L'Hospital's Rule.
Answer: −sinx. Basic trigonometric derivative.
Flashcard 27: Find the limit: limx→∞x+12x+3 using L'Hospital's Rule.
Answer:
- Apply L'Hospital's Rule: limx→∞12=2.
Flashcard 28: Identify the indeterminate form: limx→1x−1x2−1.
Answer: 00. Factoring gives (x+1)(x−1) in numerator; creates 00.
Flashcard 29: Find the derivative of ln(1+x) for L'Hospital's Rule.
Answer: 1+x1. Chain rule derivative of logarithmic function.
Flashcard 30: Find the limit: limx→∞x2+1x using L'Hospital's Rule.
Answer:
- Apply L'Hospital's Rule: limx→∞2x1=0.