Chapter 2: Problem 59
Find the limits. \(\lim \left(2-\frac{3}{t^{1 / 3}}\right) \mathrm{as}\) a. \(t \rightarrow 0^{+}\) b. \(t \rightarrow 0^{-}\)
Short Answer
Expert verified
a. \(-\infty\) b. \(+\infty\)
Step by step solution
01
Understanding the Problem
We need to find the limits of the function \( f(t) = 2 - \frac{3}{t^{1/3}} \) as \( t \) approaches zero from the positive side (\( t \to 0^+ \)), and from the negative side (\( t \to 0^- \)). This involves analyzing the behavior of the cube root term \( t^{1/3} \) when \( t \) is close to zero.
02
Analyzing Limit as t Approaches Zero from the Positive Side
When \( t \to 0^+ \), \( t^{1/3} \) is a small positive number. In this scenario, \( \frac{3}{t^{1/3}} \) becomes very large and positive, causing \( 2 - \frac{3}{t^{1/3}} \) to approach \(-\infty\). Thus, the limit is \(-\infty\).
03
Analyzing Limit as t Approaches Zero from the Negative Side
When \( t \to 0^- \), \( t^{1/3} \) becomes a small negative number. As a result, \( \frac{3}{t^{1/3}} \) becomes very large but negative, leading \( 2 - \frac{3}{t^{1/3}} \) to approach \(+\infty\). Hence, the limit is \(+\infty\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Behavior of cube roots
The cube root function presents a unique behavior that sets it apart from square roots. Let's explore how this behavior impacts our limit problem. When dealing with cube roots, the function \( t^{1/3} \) represents the cube root of \( t \). This function has a consistent behavior whether \( t \) is positive or negative, which is not the case for square roots.
- If \( t \) is positive, \( t^{1/3} \) is also positive, and shrinking \( t \) towards zero results in \( t^{1/3} \) becoming a smaller positive number.
- If \( t \) is negative, \( t^{1/3} \) becomes negative, ensuring consistent behavior asymmetrically along the negative axis. In this scenario, shrinking \( t \) towards zero results in \( t^{1/3} \) being a small negative value.
Approaching zero
Analyzing limits often involves understanding how a function behaves as its variable gets infinitesimally close to a specific value, in this case, zero. The expression \( \frac{3}{t^{1/3}} \) in the function stands out when \( t \) approaches zero. This is due to the influence of the denominator becoming a very tiny number.
- As \( t \to 0^+ \), we're looking at very small positive numbers. These numbers make \( t^{1/3} \) shrink into smaller positives, causing \( \frac{3}{t^{1/3}} \) to skyrocket to large positive values.
- Conversely, for \( t \to 0^- \), where \( t \) is a small negative, \( t^{1/3} \) also becomes a small negative. This flips \( \frac{3}{t^{1/3}} \) to large negative values because dividing by a tiny negative produces a large negative outcome.
Positive and negative limits
Limits can reveal different outcomes based on the direction from which the variable approaches a point. In this exercise, we see intriguing results depending on whether \( t \) approaches zero from the positive side or the negative side.
- When \( t \to 0^+ \), the phenomenon where very small positive cube roots lead \( \frac{3}{t^{1/3}} \) to a large positive means that \( 2 - \frac{3}{t^{1/3}} \) shoots towards \(-\infty\). This leads to the conclusion that the limit value is negative infinity.
- In contrast, with \( t \to 0^- \), the small negative cube roots turn \( \frac{3}{t^{1/3}} \) extremely negative, forcing \( 2 - \text{large negative} \) to move towards \(+\infty\). Here, the limit is positive infinity.