/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 22 Determine which of the following... [FREE SOLUTION] | 91Ó°ÊÓ

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Determine which of the following limits exist. Compute the limits that exist. $$\lim _{x \rightarrow 5} \frac{2 x-10}{x^{2}-25}$$

Short Answer

Expert verified
The limit exists and is \frac{1}{5}.\

Step by step solution

01

Identify the form of the limit

First, recognize that as x approaches 5, both the numerator and the denominator approach zero, creating an indeterminate form of \( \frac{0}{0} \).
02

Factor the expression

Factor the numerator and the denominator to simplify the expression. The numerator \(2x - 10\) can be factored as \(2(x - 5)\). The denominator \(x^2 - 25\) can be factored as \((x - 5)(x + 5)\).
03

Simplify the fraction

Simplify the expression by canceling the common factor \(x - 5\) in the numerator and the denominator: \ \frac{2(x-5)}{(x-5)(x+5)} = \frac{2}{x+5}.\
04

Compute the limit

Now substitute \(x = 5\) into the simplified expression to find the limit: \ \lim_{x \to 5} \frac{2}{x+5} = \frac{2}{5+5} = \frac{2}{10} = \frac{1}{5}.\

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

indeterminate forms
Indeterminate forms in calculus are expressions that do not have a clear value without further analysis. One of the most common indeterminate forms is \(\frac{0}{0}\). When dealing with limits, if both the numerator and the denominator approach zero as the variable approaches a certain value, like in our given problem, we end up with an indeterminate form.

Knowing that an expression is in an indeterminate form is essential. It signals that we must simplify or manipulate the expression to find a definite limit. Without recognizing these forms, computing limits accurately can become almost impossible.

Other typical indeterminate forms include \(\frac{\text{∞}}{\text{∞}}, \text{∞} - \text{∞}, 0 \times \text{∞}, 1^\text{∞}, 0^0, \text{ and } \text{∞}^0\).
factoring expressions
Factoring expressions is a key technique in simplifying functions, especially when computing limits. In the given exercise, the numerator \(2x - 10\) and the denominator \(x^2 - 25\) need to be factored to facilitate simplification.

Factoring the numerator: \(2x - 10\) can be written as \(2(x - 5)\).

Factoring the denominator: \(x^2 - 25\) is a difference of squares and can be expressed as \((x - 5)(x + 5)\).

This step is critical because it reveals common factors in the numerator and denominator that can be canceled out. Only after factoring correctly can we move on to simplifying the given expression to compute the limit effectively.
simplifying fractions
Simplifying fractions involves canceling out common factors in the numerator and the denominator. In our problem, once we factor both the numerator and the denominator, we get: \(\frac{2(x - 5)}{(x - 5)(x + 5)}\).

Here, \(x - 5\) is a common factor in both the numerator and the denominator. By canceling \(x - 5\), we simplify the fraction to: \(\frac{2}{x + 5}\).

Simplifying fractions is crucial because it removes the indeterminate form and makes it possible to directly substitute the value of the variable to find the limit. Always be cautious while canceling factors. Ensure that the factor you're canceling is common and correctly factored out.
computing limits
After simplifying the fraction, the final step is to compute the limit by substituting the variable with the value it approaches. In our problem, after simplification, the expression becomes \(\frac{2}{x + 5}\).

Now, we'll substitute \(x = 5\) into the simplified expression: \(\frac{2}{5 + 5} = \frac{2}{10} = \frac{1}{5}\).

Computing the limit involves evaluating the simplified expression at the given point. This concludes the limit problem, giving us a definite value. By simplifying the expression first, it becomes straightforward to compute the limit and avoid indeterminate forms throughout the process.

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