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Ch. 2 - Limits
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook
Chapter 2, Problem 38

Evaluate each limit and justify your answer. 
lim x→0 (x / √16x+1-1)^1/3

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Step 1: Recognize that the limit involves a form that may be indeterminate as x approaches 0. The expression inside the limit is (x / (\(\sqrt{16x+1}\) - 1))^{1/3}.
Step 2: Simplify the expression inside the limit. Notice that the denominator \(\sqrt{16x+1}\) - 1 can be rationalized. Multiply the numerator and the denominator by the conjugate \(\sqrt{16x+1}\) + 1.
Step 3: After multiplying by the conjugate, the denominator becomes a difference of squares: (\(\sqrt{16x+1}\))^2 - 1^2 = 16x. The expression now is x(\(\sqrt{16x+1}\) + 1) / 16x.
Step 4: Simplify the expression further by canceling x in the numerator and denominator, resulting in (\(\sqrt{16x+1}\) + 1) / 16.
Step 5: Evaluate the limit as x approaches 0. Substitute x = 0 into the simplified expression to find the limit of the original expression.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Limits

A limit is a fundamental concept in calculus that describes the behavior of a function as its input approaches a certain value. It helps in understanding how functions behave near points of interest, including points of discontinuity or indeterminate forms. Evaluating limits often involves techniques such as substitution, factoring, or applying L'Hôpital's rule when faced with indeterminate forms.
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Indeterminate Forms

Indeterminate forms arise in calculus when evaluating limits that do not lead to a clear numerical result, such as 0/0 or ∞/∞. These forms require further analysis or manipulation to resolve. Recognizing an indeterminate form is crucial for applying appropriate techniques, such as algebraic simplification or L'Hôpital's rule, to find the limit's value.
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Cube Roots

The cube root function, denoted as (x)^(1/3), is the inverse operation of cubing a number. It is important in limit problems involving expressions raised to fractional powers. Understanding how cube roots behave, especially near critical points like zero, is essential for accurately evaluating limits that involve such expressions, as they can affect the continuity and differentiability of the function.
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