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Ch. 3 - Derivatives
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077당신이 사용하는 게 아니라요?교과서 변경
3장, 문제 3.2.26

Using the Alternative Formula for Derivatives


Use the formula
f'(x) = lim (z → x) (f(z) − f(x)) / (z − x)
to find the derivative of the functions in Exercises 23–26.


g(x) = 1 + √x

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1
Identify the function g(x) = 1 + √x and the point at which you want to find the derivative, which is x.
Substitute g(x) into the alternative formula for derivatives: g'(x) = lim (z → x) [(g(z) − g(x)) / (z − x)].
Express g(z) in terms of z: g(z) = 1 + √z. Substitute this into the formula: g'(x) = lim (z → x) [(1 + √z − (1 + √x)) / (z − x)].
Simplify the expression inside the limit: g'(x) = lim (z → x) [(√z − √x) / (z − x)].
To evaluate the limit, multiply the numerator and the denominator by the conjugate of the numerator: (√z + √x). This will help eliminate the square roots and simplify the expression for taking the limit.

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Derivative

A derivative represents the rate at which a function is changing at any given point and is a fundamental concept in calculus. It is the limit of the average rate of change of the function over an interval as the interval approaches zero. Understanding derivatives is crucial for analyzing the behavior of functions, such as finding slopes of tangent lines and rates of change.
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Limit

A limit is a fundamental concept in calculus that describes the value a function approaches as the input approaches a certain point. Limits are essential for defining derivatives and integrals, and they help in understanding the behavior of functions at points where they may not be explicitly defined. Calculating limits involves evaluating the function's behavior as the variable approaches a specific value.
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05:50
One-Sided Limits

Alternative Formula for Derivatives

The alternative formula for derivatives, f'(x) = lim (z → x) (f(z) − f(x)) / (z − x), provides a way to calculate the derivative using limits. This formula emphasizes the concept of instantaneous rate of change by considering the difference quotient as z approaches x. It is particularly useful for functions where the standard derivative rules are not easily applicable, requiring a deeper understanding of limits and function behavior.
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