Math Problem Statement

Solve for the exact value of x in log_2(5x) + 4 log_2(3) = 5.

Solution

We are tasked with solving for xx in the equation:

log2(5x)+4log2(3)=5\log_2(5x) + 4 \log_2(3) = 5

Let's break down the steps to solve it:

Step 1: Simplify the second term

Using the logarithmic rule alogb(c)=logb(ca)a \log_b(c) = \log_b(c^a), we can simplify the second term:

4log2(3)=log2(34)=log2(81)4 \log_2(3) = \log_2(3^4) = \log_2(81)

Now the equation becomes:

log2(5x)+log2(81)=5\log_2(5x) + \log_2(81) = 5

Step 2: Combine the logarithmic terms

Using the logarithmic rule logb(a)+logb(c)=logb(ac)\log_b(a) + \log_b(c) = \log_b(ac), we can combine the two logarithmic terms on the left-hand side:

log2(5x81)=5\log_2(5x \cdot 81) = 5

This simplifies to:

log2(405x)=5\log_2(405x) = 5

Step 3: Solve for xx

To eliminate the logarithm, we rewrite the equation in exponential form:

405x=25405x = 2^5

Since 25=322^5 = 32, we have:

405x=32405x = 32

Solving for xx:

x=32405x = \frac{32}{405}

Final Answer:

The exact value of xx is:

x=32405x = \frac{32}{405}

Would you like more details on any specific step? Feel free to ask! Here are some follow-up questions you might find useful:

  1. What are the properties of logarithms that help in solving logarithmic equations?
  2. How can logarithms with different bases be handled?
  3. Why is it useful to rewrite logarithmic equations in exponential form?
  4. Can the solution for xx in this equation be checked by substitution?
  5. What other methods exist for solving logarithmic equations like this?

Tip: When solving logarithmic equations, always look for opportunities to combine logarithmic terms using properties like the product and power rules.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Exponential Equations
Algebra

Formulas

log_b(a) + log_b(c) = log_b(ac)
a log_b(c) = log_b(c^a)
log_b(a) = n means b^n = a

Theorems

Laws of Logarithms

Suitable Grade Level

Grades 10-12