/*! 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 68 Find the derivative of \(y\) wit... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Find the derivative of \(y\) with respect to the given independent variable. $$y=3^{-x}$$

Short Answer

Expert verified
The derivative is \(-3^{-x} \ln(3)\).

Step by step solution

01

Identify the Problem

We need to find the derivative of the given function, which is expressed as an exponential function: \( y = 3^{-x} \). The goal is to determine \( \frac{dy}{dx} \), the derivative of \( y \) with respect to \( x \).
02

Apply the Exponential Derivative Rule

To find the derivative of an expression of the form \( a^{f(x)} \), use the rule: \( \frac{d}{dx}[a^{f(x)}] = a^{f(x)} \ln(a) \cdot f'(x) \), where \( a \) is a constant. Here, \( a = 3 \) and \( f(x) = -x \).
03

Calculate the Derivative of the Exponent

Find the derivative of \( f(x) = -x \) with respect to \( x \). The derivative, \( f'(x) \), is simply \( -1 \) since the derivative of \( x \) is 1 and we have a negative sign.
04

Substitute into the Derivative Formula

Substitute \( f(x) = -x \), \( f'(x) = -1 \), and \( a = 3 \) into the exponential derivative formula: \[ \frac{dy}{dx} = 3^{-x} \ln(3) \cdot (-1) \].
05

Simplify the Expression

Simplify the expression for the derivative: \[ \frac{dy}{dx} = -3^{-x} \ln(3) \]. This is the simplified expression for the derivative of the given function.

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Key Concepts

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

Exponential Function
An exponential function is a type of mathematical expression where the variable is the exponent. This function takes the form of \( y = a^x \), where \( a \) is a positive constant, known as the base, and \( x \) is the exponent. Exponential functions are widely used in different fields such as finance, biology, and physics because they describe exponential growth or decay.
  • For growth, the base \( a \) is greater than 1, indicating that as \( x \) increases, so does \( y \).
  • For decay, the base \( a \) is between 0 and 1, meaning that as \( x \) increases, \( y \) decreases.
In our original exercise, the function \( y = 3^{-x} \) is an example of exponential decay because the exponent \(-x\) causes the value of \( y \) to decrease as \( x \) increases.
Exponential Derivative Rule
The exponential derivative rule is a handy tool for finding the derivative of an exponential function. This rule states that if you have a function in the form of \( a^{f(x)} \), its derivative is given by:
  • \( \frac{d}{dx}[a^{f(x)}] = a^{f(x)} \ln(a) \cdot f'(x) \)
Here is a breakdown of the components:
  • \( a^{f(x)} \) stays in the expression, meaning the exponential part remains the same.
  • \( \ln(a) \) is the natural logarithm of the base, which is constant for a specific \( a \).
  • \( f'(x) \) is the derivative of the exponent \( f(x) \), detailing how \( x \) changes.
In the given problem, since \( f(x) = -x \), we use this rule by substituting the appropriate values for \( f(x) \) and its derivative \( f'(x) \).
This allows us to compute \( \frac{dy}{dx} \) with ease.
Derivative of Exponential Functions
Finding the derivative of an exponential function, particularly one with a negative exponent as given in \( y = 3^{-x} \), involves applying the exponential derivative rule correctly.
  • The function \( y = 3^{-x} \) maps onto the rule as \( a^{f(x)} = 3^{-x} \).
  • The derivative of \( f(x) = -x \) is \( f'(x) = -1 \).
  • Substituting these values back into the derivative rule results in:
    \( \frac{dy}{dx} = 3^{-x} \ln(3) \cdot (-1) \).
By simplifying this, we see that the negative sign from \( f'(x) = -1 \) factors into the result, giving us the final expression:
\( \frac{dy}{dx} = -3^{-x} \ln(3) \).
This simplified form provides a clear understanding of how the rate of change in \( y \) corresponds to changes in \( x \), while taking into account the base and its natural logarithm.

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