Math Problem Statement

Solve for the exact value of x: log_5(9x) + 2log_5(3) = 2

Solution

Let's solve the equation step by step:

We are given the equation:

log5(9x)+2log5(3)=2\log_5(9x) + 2\log_5(3) = 2

Step 1: Apply the logarithmic identity

We know that 2logb(a)=logb(a2)2\log_b(a) = \log_b(a^2). Applying this to the second term, we get:

log5(9x)+log5(32)=2\log_5(9x) + \log_5(3^2) = 2

This simplifies to:

log5(9x)+log5(9)=2\log_5(9x) + \log_5(9) = 2

Step 2: Combine the logarithms

Since we have the sum of two logarithms with the same base, we can use the logarithmic property logb(a)+logb(c)=logb(ac)\log_b(a) + \log_b(c) = \log_b(a \cdot c). Applying this, we get:

log5(9x9)=2\log_5(9x \cdot 9) = 2

Simplifying inside the logarithm:

log5(81x)=2\log_5(81x) = 2

Step 3: Remove the logarithm

To remove the logarithm, we rewrite the equation in exponential form. If logb(a)=c\log_b(a) = c, then a=bca = b^c. Applying this to the equation:

81x=5281x = 5^2

Simplifying:

81x=2581x = 25

Step 4: Solve for xx

Now, solve for xx by dividing both sides by 81:

x=2581x = \frac{25}{81}

Thus, the exact value of xx is:

x=2581x = \frac{25}{81}

Would you like more details on any step or have further questions?


Here are five related questions to explore further:

  1. What is the general rule for combining logarithms with the same base?
  2. How do you convert a logarithmic equation to its exponential form?
  3. Can the property 2logb(a)=logb(a2)2\log_b(a) = \log_b(a^2) be extended to other powers?
  4. How would the solution change if the base of the logarithms was different?
  5. How can logarithmic identities simplify solving exponential equations?

Tip: Always check whether you can simplify logarithmic expressions by using properties like the product rule, power rule, or change of base formula!

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Math Problem Analysis

Mathematical Concepts

Logarithms
Logarithmic identities
Exponential equations

Formulas

log_b(a) + log_b(c) = log_b(a * c)
2log_b(a) = log_b(a^2)
log_b(a) = c implies a = b^c

Theorems

Logarithmic properties
Exponential form of logarithms

Suitable Grade Level

Grades 10-12