Chapter 6: Problem 41
Solve each logarithmic equation. Express all solutions in exact form. Support your solutions by using a calculator. $$\log _{4}\left(x^{3}+37\right)=3$$
Short Answer
Expert verified
The solution is \( x = 3 \).
Step by step solution
01
Understanding the Logarithmic Equation
The given equation is \( \log_{4}(x^3 + 37) = 3 \). This means that the logarithm base 4 of \( x^3 + 37 \) equals 3. According to the definition of logarithms, this implies that \( 4^3 = x^3 + 37 \). Our goal is to solve for \( x \).
02
Exponentiating the Expression
Since \( \log_{4}(x^3 + 37) = 3 \) implies \( x^3 + 37 = 4^3 \), we need to calculate \( 4^3 \). Calculate this to find that \( 4^3 = 64 \). Thus, the equation becomes \( x^3 + 37 = 64 \).
03
Isolating the Variable Term
To isolate \( x^3 \), subtract 37 from both sides:\[ x^3 + 37 - 37 = 64 - 37 \]\[ x^3 = 27 \].
04
Solving for x
Now, solve for \( x \) by finding the cube root of both sides of the equation:\[ x = \sqrt[3]{27} = 3 \].
05
Verifying the Solution
Confirm by substituting \( x = 3 \) back into the original equation:\[ \log_{4}(3^3 + 37) = \log_{4}(27 + 37) = \log_{4}(64) \].Since \( 64 = 4^3 \), \( \log_{4}(64) = 3 \) which matches our original equation, confirming that \( x = 3 \) is correct.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exponents
Exponents are a mathematical way to express repeated multiplication of a number by itself. For instance, in our equation, we have an expression like \( 4^3 \). This means \( 4 \) is multiplied by itself three times, resulting in 64. Exponents are common in algebra and are crucial for solving many types of equations, including logarithmic ones.
- In an expression \( a^b \), \( a \) is the base and \( b \) is the exponent.
- The result shows how many times the base is multiplied by itself.
- Exponents follow specific rules, like \( a^0 = 1 \) (for any non-zero \( a \)) and \( a^1 = a \).
Cube Roots
Cube roots are the inverse operation of cubing a number. When you take the cube root of a number, you're finding a value that, when multiplied by itself twice, equals the original number. For instance, the cube root of 27 is 3, since \( 3 \times 3 \times 3 = 27 \).
- The cube root of a number \( a \) is denoted as \( \sqrt[3]{a} \).
- Cube roots help solve equations where a variable is cubed, as seen in \( x^3 = 27 \).
Logarithmic Functions
Logarithmic functions are the inverses of exponential functions. They help to solve equations where the variable is an exponent, like in \( \log_4(x^3 + 37) = 3 \). The function tells us the power we must raise the base to achieve a specific number.
- In \( \log_b(a) = c \), \( b^c = a \) shows the link between logarithms and exponents.
- Logarithms have distinctive properties like \( \log_b(mn) = \log_b(m) + \log_b(n) \) and \( \log_b(\frac{m}{n}) = \log_b(m) - \log_b(n) \).
- They are used in many fields, from science to engineering, for calculations involving exponential growth or decay.