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Exponential Equations

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College Algebra

Definition

Exponential equations are mathematical expressions where the unknown variable appears as the exponent. These equations describe situations where a quantity grows or decays at a constant rate over time, and they are commonly used to model real-world phenomena such as population growth, radioactive decay, and compound interest.

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5 Must Know Facts For Your Next Test

  1. Exponential equations can be used to model situations where a quantity grows or decays at a constant rate, such as population growth, radioactive decay, and compound interest.
  2. The general form of an exponential equation is $a^x = b$, where $a$ is the base, $x$ is the unknown variable, and $b$ is the output value.
  3. Solving exponential equations often involves using logarithms to convert the equation to a linear form, making it easier to isolate the unknown variable.
  4. The rate of change in an exponential equation is determined by the base, $a$, where a value greater than 1 indicates growth, and a value between 0 and 1 indicates decay.
  5. Exponential equations are closely related to the concept of exponents, which represent repeated multiplication of a base number.

Review Questions

  • Explain how exponential equations are used to model real-world phenomena, and provide an example of a situation where an exponential equation would be appropriate.
    • Exponential equations are used to model situations where a quantity grows or decays at a constant rate over time. For example, the growth of a population can be described by an exponential equation, where the population size increases by a fixed percentage each time period. Another example is the decay of radioactive materials, where the amount of radioactive material decreases exponentially over time. In these cases, the exponential equation allows us to predict the future value of the quantity based on the initial value and the constant rate of change.
  • Describe the relationship between exponential equations and logarithms, and explain how logarithms can be used to solve exponential equations.
    • Exponential equations and logarithms are closely related, as logarithms are the inverse operation of exponents. When solving an exponential equation in the form $a^x = b$, we can use logarithms to convert the equation to a linear form. By taking the logarithm of both sides of the equation, we get $x = \log_a b$, which allows us to isolate the unknown variable $x$. This is particularly useful when the base $a$ is not 1, as logarithms can help simplify the equation and make it easier to solve for the unknown.
  • Analyze the factors that influence the rate of change in an exponential equation, and explain how the base, $a$, affects the growth or decay of the quantity being modeled.
    • The rate of change in an exponential equation is determined by the base, $a$. When $a$ is greater than 1, the equation models exponential growth, where the quantity increases by a constant percentage over time. Conversely, when $a$ is between 0 and 1, the equation models exponential decay, where the quantity decreases by a constant percentage over time. The specific value of $a$ determines the steepness of the growth or decay curve, with higher values of $a$ resulting in faster growth or decay. Understanding the relationship between the base and the rate of change is crucial for accurately modeling and predicting the behavior of exponential phenomena.

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