Chapter 4: Problem 6
Find the limit. Use l'Hospital's Rule where appropriate. If there is a more elementary method, consider using it. If l'Hospital's Rule doesn't apply, explain why. \(\lim _{t \rightarrow 0} \frac{e^{3 t}-1}{t}\)
Short Answer
Expert verified
The limit is 3.
Step by step solution
01
Identify the Indeterminate Form
First, plug in the value of \( t = 0 \) in the expression. This gives \( \frac{e^{3 \cdot 0} - 1}{0} = \frac{1 - 1}{0} = \frac{0}{0} \). This is an indeterminate form, which means we can consider using l'Hospital's Rule.
02
Apply l'Hospital's Rule
Since the expression is in the form \( \frac{0}{0} \), l'Hospital's Rule can be used, which states that \( \lim_{x \to a} \frac{f(x)}{g(x)} = \lim_{x \to a} \frac{f'(x)}{g'(x)} \) if this limit exists. Here, set \( f(t) = e^{3t} - 1 \) and \( g(t) = t \).
03
Differentiate Numerator and Denominator
Calculate the derivative of the numerator: \( f'(t) = \frac{d}{dt}[e^{3t} - 1] = 3e^{3t} \). Calculate the derivative of the denominator: \( g'(t) = \frac{d}{dt}[t] = 1 \).
04
Apply the Derivatives in the Limit
Now apply l'Hospital's Rule: \( \lim_{t \to 0} \frac{3e^{3t}}{1} = 3e^{3 \cdot 0} = 3 \cdot 1 = 3 \).
05
Conclusion
Since the limit using l'Hospital's Rule results in a finite number, \( 3 \), we have successfully found the limit.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
L'Hospital's Rule
L'Hospital's Rule is a powerful tool in calculus, designed to help find limits that present indeterminate forms. Often, when calculating limits, we run into expressions like \( \frac{0}{0} \) or \( \frac{\infty}{\infty} \). These are called indeterminate forms because they don't provide a clear answer about the value of a limit just by initial substitution. L'Hospital's Rule provides a method for resolving these by taking derivatives.
Here's how it works:
Here's how it works:
- Identify the indeterminate form. Common forms include \( \frac{0}{0} \) or \( \frac{\infty}{\infty} \).
- Ensure the limit itself is valid for L'Hospital's Rule. This means both the numerator and denominator must be differentiable near the point of interest.
- Apply the rule: Replace the limit of the original fraction with the limit of the fraction of their derivatives. In other words, if \( \lim_{x \to a} \frac{f(x)}{g(x)} \) results in an indeterminate form, try \( \lim_{x \to a} \frac{f'(x)}{g'(x)} \).
- Finally, calculate the new limit. If it is still indeterminate, L'Hospital's Rule may be applied repeatedly if necessary.
Limits
Limits are foundational in calculus, capturing the behavior of a function as it approaches a specific point. The notation \( \lim_{x \to a} f(x) \) helps us understand what value \( f(x) \) approaches as \( x \) gets closer to \( a \). Calculating limits involves predicting the value a function seems to be heading towards without necessarily reaching it.
Understanding limits enhances comprehension of functions' overall behavior. They aid in:
Understanding limits enhances comprehension of functions' overall behavior. They aid in:
- Determining continuity by checking if \( \lim_{x \to a} f(x) = f(a) \).
- Calculating derivatives, which are expressed as a limit themselves.
- Identifying asymptotic behavior, understanding functions near undefined points or infinity.
Indeterminate Forms
Indeterminate Forms cause difficulties when calculating limits, often giving expressions like \( \frac{0}{0} \) or \( \frac{\infty}{\infty} \). These forms don't have a simple numerical value, leading to ambiguities. When faced with such forms, direct substitution may not yield meaningful results.
To solve limits involving indeterminate forms, one can:
To solve limits involving indeterminate forms, one can:
- Use algebraic manipulation to simplify the expression.
- Apply L'Hospital's Rule where appropriate to differentiate the numerator and denominator until a clear limit value emerges.
- Factor or rationalize expressions to remove the indeterminate form.