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Ch. 3 - Derivatives
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook
All textbooksBriggs 3rd EditionCh. 3 - DerivativesProblem 3.9.44
Chapter 3, Problem 3.9.44

15–48. Derivatives Find the derivative of the following functions.
P = 40/1+2^-t

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Step 1: Identify the function P(t) = \(\frac{40}{1 + 2^{-t}\)}. This is a rational function where the numerator is a constant and the denominator is a function of t.
Step 2: Apply the quotient rule for derivatives, which states that if you have a function \(\frac{u(t)}{v(t)}\), its derivative is \(\frac{u'(t)v(t) - u(t)v'(t)}{(v(t))^2}\). Here, u(t) = 40 and v(t) = 1 + 2^{-t}.
Step 3: Calculate u'(t). Since u(t) = 40, which is a constant, its derivative u'(t) = 0.
Step 4: Calculate v'(t). The function v(t) = 1 + 2^{-t} involves an exponential term. The derivative of 2^{-t} with respect to t is -2^{-t} \(\ln\)(2), using the chain rule.
Step 5: Substitute u'(t), u(t), v(t), and v'(t) into the quotient rule formula: \(\frac{0 \cdot (1 + 2^{-t}\)) - 40 \(\cdot\) (-2^{-t} \(\ln\)(2))}{(1 + 2^{-t})^2}. Simplify the expression to find the derivative of P(t).

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Key Concepts

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

Derivatives

A derivative represents the rate at which a function changes at any given point. It is a fundamental concept in calculus that measures how a function's output value changes as its input value changes. The derivative can be interpreted as the slope of the tangent line to the curve of the function at a specific point.
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Chain Rule

The chain rule is a formula for computing the derivative of a composite function. If a function is composed of two or more functions, the chain rule allows us to differentiate it by multiplying the derivative of the outer function by the derivative of the inner function. This is particularly useful when dealing with functions that include exponentials or other transformations.
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Exponential Functions

Exponential functions are mathematical functions of the form f(t) = a * b^t, where 'a' is a constant, 'b' is the base of the exponential, and 't' is the exponent. These functions are characterized by their rapid growth or decay and are commonly encountered in calculus. Understanding their properties is essential for differentiating functions that involve exponential terms.
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