Chapter 5: Problem 7
Find the limits. $$ \lim _{x \rightarrow-\infty} \sqrt[3]{x} $$
Short Answer
Expert verified
The limit is \(-\infty\).
Step by step solution
01
Understand the Function
The function we need to find the limit for as \(x\) approaches \(-\infty\) is \( \sqrt[3]{x} \), which is the cube root of \(x\). The cube root function \( \sqrt[3]{x} \) is defined for all real numbers, including negative ones.
02
Analyze the Behavior as \(x\) Approaches \(-\infty\)
When \(x\) is a very large negative number, the cube root \(\sqrt[3]{x}\) will also be a negative number because the cube of any negative number is negative. As \(x\) becomes more negative, \( \sqrt[3]{x} \) will become more negative as well.
03
Determine the Limit
Since as \(x\) approaches \(-\infty\), \( \sqrt[3]{x} \) continues to decrease and does not have any boundary, the limit \( \lim_{x \rightarrow -\infty} \sqrt[3]{x} \) is also \(-\infty\).
04
Conclude the Solution
Thus, we conclude that the limit of \( \sqrt[3]{x} \) as \(x\) approaches \(-\infty\) is \(-\infty\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Cube Root Function
The cube root function, denoted as \( \sqrt[3]{x} \), is a mathematical operation that returns a number whose cube is \( x \). Unlike the square root function, cube roots operate over both positive and negative numbers without restriction. This is because cubing a negative number results in a negative number, making cube roots always defined for real numbers.
Cube root functions exhibit interesting characteristics:
Cube root functions exhibit interesting characteristics:
- They are continuous and defined for all real numbers \( x \).
- For positive \( x \), both roots are positive, and for non-positive \( x \), the root is negative or zero.
- This function is odd, meaning \( \sqrt[3]{-x} = -\sqrt[3]{x} \), which highlights its symmetry around the origin.
Infinite Limits
Infinite limits are a fundamental concept in calculus that describe the behavior of a function as the input, often represented as \( x \), tends toward infinity or negative infinity. In the context of our example, \( \lim_{x \rightarrow -\infty} \sqrt[3]{x} \), we're interested in how \( \sqrt[3]{x} \) behaves as \( x \) decreases without bound.
Here's why understanding infinite limits is crucial:
Here's why understanding infinite limits is crucial:
- They help to describe the end behavior of functions, providing insight into function growth or decay.
- Understanding this concept is essential for identifying asymptotes and determining the long-term trends of functions.
- Specific to cube root functions, because they can take any real number, the result as \( x \) approaches negative infinity is a negative infinity.
Asymptotic Behavior
Asymptotic behavior analyzes how a function behaves as its input grows really large (positively or negatively). For our exercise, we're exploring \( \lim_{x \rightarrow -\infty} \sqrt[3]{x} \), looking at its trend as \( x \) becomes infinitely negative.
This concept is tightly connected to limits and brings critical insights:
This concept is tightly connected to limits and brings critical insights:
- An asymptote is a line that the graph of a function can approach but never actually reach.
- In our case, the cube root function doesn't have horizontal asymptotes since it doesn't level off or flatten out.
- Instead, its asymptotic behavior shows a continual decrease as \( x \) heads toward \(-\infty\).