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Solve the exponential equations. Make sure to isolate the base to a power first. Round our answers to three decimal places. $$\frac{20}{6-e^{2 x}}=4$$

Short Answer

Expert verified
The solution is \( x = 0 \).

Step by step solution

01

Eliminate the fraction

To eliminate the fraction on the left side of the equation \( \frac{20}{6-e^{2x}} = 4 \), multiply both sides by \( 6 - e^{2x} \). This gives us: \[ 20 = 4(6 - e^{2x}) \]
02

Expand the equation

Expand the right side of the equation: \[ 20 = 24 - 4e^{2x} \]
03

Isolate the exponential term

Subtract 24 from both sides to isolate the term involving \( e^{2x} \): \[ 20 - 24 = -4e^{2x} \] \[ -4 = -4e^{2x} \]
04

Simplify the equation

Divide both sides by -4 to solve for \( e^{2x} \): \[ 1 = e^{2x} \]
05

Solve for \( x \)

Take the natural logarithm of both sides to solve for \( x \). Since \( \ln(e^{2x}) = 2x \cdot \ln(e) = 2x \), the equation becomes: \[ \ln(1) = 2x \] \[ 0 = 2x \]
06

Calculate \( x \)

Divide both sides by 2 to find \( x \): \[ x = 0 \]

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Key Concepts

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

Solving Exponential Equations
When tasked with solving exponential equations, it is important to manipulate the equation to find the unknown variable, often denoted as \( x \). Exponential equations involve expressions where the variable appears in the exponent, such as \( e^{2x} \). The key to solving these equations is to successfully isolate the exponential part on one side of the equation, allowing us to then apply logarithmic methods to solve for the variable.

Here's a simple approach to tackle these types of problems:
  • Start by removing any fractions or complex expressions by performing algebraic operations like multiplication or division.
  • Next, isolate the term that includes the exponential expression, making it easier to apply logarithms.
  • Once isolated, use logarithms to take the exponent down to a base level equation.
  • Solve for the variable, and ensure to simplify your answer appropriately.
It's crucial to follow these steps to maintain clarity and precision in your calculations.
Understanding Natural Logarithms
The natural logarithm, denoted as \( \ln \), is a critical tool in solving exponential equations. It is the logarithm to the base \( e \), where \( e \) is an irrational constant approximately equal to 2.71828. This type of logarithm is particularly useful with exponential functions that use \( e \) as the base.

Using \( \ln \) helps us transform and simplify expressions involving powers of \( e \). In our case, after isolating \( e^{2x} \), taking the natural logarithm on both sides of the equation allows us to handle the exponent:
  • For instance, for the equation \( e^{2x} = 1 \), taking the natural logarithm yields \( \ln(e^{2x}) = 2x \cdot \ln(e) \).
  • Since \( \ln(e) = 1 \), the equation simplifies to \( 2x = \ln(1) \).
  • Knowing that \( \ln(1) = 0 \), we solve for \( x \) easily.

The natural logarithm thus efficiently simplifies solving exponential equations and is a fundamental concept in algebra used frequently in both simple and complex mathematical problems.
Isolating the Base in Exponential Equations
Isolating the base in an exponential equation is a strategic step necessary to solve the equation effectively. Here, the 'base' refers to the core exponential part involving the unknown variable.

To isolate the base, take these steps:
  • Begin by addressing any constants or coefficients that coexist with the exponential term. This might involve adding, subtracting, multiplying, or dividing both sides of the equation.
  • In the equation \( 20 = 24 - 4e^{2x} \), isolating \( e^{2x} \) requires removing \( 24 \) from the right-hand side to get to \( -4e^{2x} \), and then dividing by -4 to solve for \( e^{2x} \).
  • Through these operations, you obtain \( e^{2x} = 1 \).
Once isolated, you can then apply logarithms to further simplify and solve for the variable. This procedural approach ensures all operations are valid and systematic, leading to an accurate solution.
Rounding Numbers in Solutions
Rounding numbers is a necessary practice in mathematics, especially when solutions result in repeating decimals or when precision is less critical but consistent reporting is needed. In the context of solving exponential equations, rounding helps present solutions in a clear and concise manner.

When you round to three decimal places, you follow these guidelines:
  • Identify the fourth decimal place—this determines if you round up or down.
  • If the fourth decimal is 5 or more, increase the third decimal by 1.
  • If it's less than 5, keep the third decimal as is.
For example, if a solution or calculation provides \( x = 0.123456 \), rounding to three decimal places would result in \( x = 0.123 \).

Rounding ensures results are practical for use in further applications without unnecessary complexity. It maintains uniformity across calculations ensuring consistent reporting in academic and real-world scenarios.

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Most popular questions from this chapter

Write each expression as a single logarithm. $$3 \log _{b} x-\log _{b} y$$

Evaluate exactly (without using a calculator). For rational exponents, consider converting to radical form first. $$8^{2 / 3}$$

Explain the mistake that is made. Solve the equation: \(\log x+\log 2=\log 5\) Solution: Combine the logarithms on the left. \(\quad \log (x+2)=\log 5\) Apply the property of one-to-one functions. \(x+2=5\) Solve for \(x\) \(x=3\) This is incorrect. What mistake was made?

Explain the mistake that is made. Solve the equation: \(4 e^{x}=9\) Solution: Take the natural log of both sides. \(\quad \ln \left(4 e^{x}\right)=\ln 9\) Apply the property of inverses. \(4 x=\ln 9\) \(x=\frac{\ln 9}{4} \approx 0.55\) Solve for \(x\) This is incorrect. What mistake was made?

Use the following formula for Newton’s Law of Cooling: If you take a hot dinner out of the oven and place it on the kitchen countertop, the dinner cools until it reaches the temperature of the kitchen. Likewise, a glass of ice set on a table in a room eventually melts into a glass of water at that room temperature. The rate at which the hot dinner cools or the ice in the glass melts at any given time is proportional to the difference between its temperature and the temperature of its surroundings (in this case, the room). This is called Newton's law of cooling (or warming) and is modeled by $$T=T_{S}+\left(T_{0}-T_{S}\right) e^{-k t}$$ where \(T\) is the temperature of an object at time \(t, T_{s}\) is the temperature of the surrounding medium, \(T_{0}\) is the temperature of the object at time \(t=0, t\) is the time, and \(k\) is a constant. A body is discovered in a hotel room. At 7: 00 A.M. a police detective found the body's temperature to be \(85^{\circ} \mathrm{F}\). At 8: 30 A.M. a medical examiner measures the body's temperature to be \(82^{\circ} \mathrm{F}\). Assuming the room in which the body was found had a constant temperature of \(74^{\circ} \mathrm{F}\), how long has the victim been dead? (Normal body temperature is \(98.6^{\circ} \mathrm{F} .\) ).

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