Chapter 2: Problem 41
Find the limits. $$\lim _{x \rightarrow-8^{+}} \frac{2 x}{x+8}$$
Short Answer
Expert verified
The limit is \(-\infty\).
Step by step solution
01
Identify the Limit Expression
Start by recognizing the expression for which you need to find the limit: \( \lim _{x \rightarrow -8^{+}} \frac{2x}{x+8} \). We are interested in the behavior of the function as \( x \) approaches \( -8 \) from the right side (positive direction).
02
Substitute and Simplify the Denominator Behavior
Substitute a value into the denominator \( x+8 \) that is slightly greater than \(-8\) (such as \(-8+0.01\) or exactly \(-8^+\)) to see the behavior. This results in a small positive number because any value just greater than \(-8\) will leave \( x+8 > 0 \).
03
Analyze the Numerator Behavior
Similarly, replacing \( x \) with a value slightly greater than \(-8\), the numerator \( 2x \) will approach \( 2(-8) = -16 \). Thus, the numerator heads for a constant negative value.
04
Evaluate the Behavior of the Fraction
Since the numerator approaches \(-16\) and the denominator approaches a small positive number, the expression \( \frac{2x}{x+8} \) then heads toward \(-\infty\) because a constant negative divided by a very small positive is a very large negative number.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Right-hand limit
When we talk about the right-hand limit of a function, we are looking at how the function behaves as the input value approaches a certain point from the right side. This means that for a point \( c \), we examine \( x \) values that are greater than \( c \) but still very close to it. In our exercise, we are evaluating \( \lim _{x \rightarrow -8^{+}} \frac{2x}{x+8} \), where "-8" is the point of interest, and the "+" indicates approaching from the right.
- Imagine you're inching closer to -8 from numbers like -7, getting closer and closer while keeping to the right.
- It's like driving toward a parking spot, almost getting in but from just one side of the car.
Behavior near a point
Understanding the behavior of a function near a specific point involves examining how the values of the function alter as we approach that point from either side. For instance, in our exercise, we focused on the point \( -8 \). We evaluated values such as \( x = -7.99 \) or \( x = -8+0.01 \), slightly more than -8, to see how the function behaves in that region.
- In our example, as we approach from the right, the denominators (\(x + 8\)) become tiny positive numbers.
- Simultaneously, the numerator (\(2x\)) becomes a constant negative, namely -16.
Evaluating infinite limits
Evaluating infinite limits involves determining what happens to a function as it tends towards extremely large positive or negative numbers. This can help us predict the end behavior of a function, understanding whether it blows up to infinity or collapses to negative infinity. In the case of our example, as \( x \to -8^+ \), the denominator \( x+8 \) becomes increasingly small but positive, and the numerator stays negative, specifically approaching -16.
- Picture the scenario: The fraction \( \frac{-16}{0.0001} \) contrasts to \( \frac{-16}{0.001} \); as the denominator gets smaller, the overall number grows more negative and large in magnitude.
- This indicates that our limit evaluates to \(-\infty\).