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Solve the exponential equation. $$2^{x+3}=256$$

Short Answer

Expert verified
The solution to the exponent equation \(2^{x+3} = 256\) is \(x = 5\).

Step by step solution

01

Express Both Sides of the Equation with the Same Base

Notice that 256 is a power of 2, specifically \(2^8\). This allows us to rewrite the equation as follows: \[2^{x+3} = 2^8\]
02

Apply the Same Base Rule of Exponents

Having both sides of the equation with the same base (2), according to the 'same base rule of exponents', the exponent must be the same on both sides. Thus, we can equate \(x+3\) to 8.
03

Solve for the Unknown (x)

Solving for x involves subtracting 3 from both sides of the equation: \[x+3 = 8 \ x = 8 - 3 = 5\]

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Key Concepts

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

Rule of Exponents
The Rule of Exponents is a set of guidelines that help us to simplify and manipulate expressions involving powers. The solutions to exponential equations like \(2^{x+3}=256\) often rely on these rules. Here are some of the fundamental rules you might encounter:
  • Product of Powers Rule: When you multiply like bases, keep the base the same and add the exponents: \(a^m \cdot a^n = a^{m+n}\).
  • Quotient of Powers Rule: When dividing like bases, keep the base and subtract the exponents: \(a^m / a^n = a^{m-n}\).
  • Power of a Power Rule: When raising a power to another power, multiply the exponents: \((a^m)^n = a^{mn}\).
In the original exercise, the step involving expressing both sides with the same base makes use of the Rule of Exponents. Specifically, the ability to equate exponents when the bases are identical is a powerful aspect of these rules.
This applies because once both sides of the equation were expressed with the base of 2, the equation \(x+3 = 8\) could be derived directly.
Solving Exponential Equations
Solving exponential equations involves finding the value of the variable that makes an equation true when the variable is in the exponent. This type of equation typically arises in models of exponential growth or decay, such as population dynamics or radioactive decay.
To solve the equation \(2^{x+3}=256\), we followed a series of logical steps. First, express both sides with the same base. In this case, recognizing that 256 can be written as \(2^8\) is crucial. This allows us to set the equation as \(2^{x+3} = 2^8\). Then, applying the knowledge that if two powers with the same base are equal, their exponents must be equal, we set \(x + 3 = 8\). A simple subtraction gives us \(x = 5\).
The beauty of solving exponential equations lies in how you can simplify complicated expressions once you identify common bases on both sides of the equation.
Exponential Functions
Exponential functions are mathematical expressions where a constant base is raised to a variable exponent. They frequently appear in real-world scenarios where quantities grow or decay at constant rates. These functions are of the form \(y = a^x\), where:
  • \(a\): base – reflects the initial amount and rate of growth or decay.
  • \(x\): exponent – usually represents time or related variable.
Understanding exponential functions offers insight into the behavior of various processes and forms the backbone of the solution process for exponential equations.
In mathematical models, exponential functions describe phenomena such as:
  • Population growth: where a small population rapidly increases over time.
  • Compound interest: illustrating how investments grow exponentially due to repeated periods.
  • Radioactive decay: detailing the reduction of substance over time.
The original equation, \(2^{x+3}=256\), fits within the framework of exponential functions, as both sides relate to powers of 2, showcasing their widespread utility and importance.

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Most popular questions from this chapter

Solve the logarithmic equation algebraically. Round the result to three decimal places. Verify your answer(s) using a graphing utility. $$\log _{4} x-\log _{4}(x-1)=\frac{1}{2}$$

A beaker of liquid at an initial temperature of \(78^{\circ} \mathrm{C}\) is placed in a room at a constant temperature of \(21^{\circ} \mathrm{C}\) The temperature of the liquid is measured every 5 minutes for a period of \(\frac{1}{2}\) hour. The results are recorded in the table, where \(t\) is the time (in minutes) and \(T\) is the temperature (in degrees Celsius). $$\begin{array}{|c|c|}\hline \text { Time, } t 0 & \text { Temperature, } T\\\\\hline 0 & 78.0^{\circ} \\\5 & 66.0^{\circ} \\\10 & 57.5^{\circ} \\\15 & 51.2^{\circ} \\\20 & 46.3^{\circ} \\\25 & 42.5^{\circ} \\\30 & 39.6^{\circ} \\\\\hline\end{array}$$ (a) Use the regression feature of a graphing utility to find a linear model for the data. Use the graphing utility to plot the data and graph the model in the same viewing window. Do the data appear linear? Explain. (b) Use the regression feature of the graphing utility to find a quadratic model for the data. Use the graphing utility to plot the data and graph the model in the same viewing window. Do the data appear quadratic? Even though the quadratic model appears to be a good fit, explain why it might not be a good model for predicting the temperature of the liquid when \(t=60.\) (c) The graph of the temperature of the room should be an asymptote of the graph of the model. Subtract the room temperature from each of the temperatures in the table. Use the regression feature of the graphing utility to find an exponential model for the revised data. Add the room temperature to this model. Use the graphing utility to plot the original data and graph the model in the same viewing window. (d) Explain why the procedure in part (c) was necessary for finding the exponential model.

Solve the logarithmic equation algebraically. Round the result to three decimal places. Verify your answer(s) using a graphing utility. $$\log _{10} 8 x-\log _{10}(1+\sqrt{x})=2$$

Use a graphing utility to create a scatter plot of the data. Decide whether the data could best be modeled by a linear model, an exponential model, or a logarithmic model. $$(1,2.0),(1.5,3.5),(2,4.0),(4,5.8),(6,7.0),(8,7.8)$$

Solve the logarithmic equation algebraically. Round the result to three decimal places. Verify your answer(s) using a graphing utility. $$\ln 2 x=1.5$$

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