Math Problem Statement

solve to find x: log 3 x^3 - 4log9 x - 5 log 27 sqrtx = log 9 4

Solution

To solve the equation log3(x3)4log9(x)5log27(x)=log9(4)\log_3 (x^3) - 4 \log_9 (x) - 5 \log_{27} (\sqrt{x}) = \log_9 (4), we'll start by converting all logarithms to the same base, preferably base 3, and simplifying step by step.

Step 1: Convert logarithms to base 3

We'll use the change of base formula: logb(a)=logc(a)logc(b)\log_b (a) = \frac{\log_c (a)}{\log_c (b)} We know that log9(x)=12log3(x)\log_9 (x) = \frac{1}{2} \log_3 (x) since 9=329 = 3^2, and similarly, log27(x)=13log3(x)\log_{27} (x) = \frac{1}{3} \log_3 (x) since 27=3327 = 3^3.

The right-hand side log9(4)\log_9 (4) can also be written as: log9(4)=12log3(4)\log_9 (4) = \frac{1}{2} \log_3 (4)

Thus, the equation becomes: log3(x3)4(12log3(x))5(13log3(x1/2))=12log3(4)\log_3 (x^3) - 4 \left( \frac{1}{2} \log_3 (x) \right) - 5 \left( \frac{1}{3} \log_3 (x^{1/2}) \right) = \frac{1}{2} \log_3 (4)

Step 2: Simplify logarithmic terms

Now let's simplify each term:

  • log3(x3)=3log3(x)\log_3 (x^3) = 3 \log_3 (x)
  • The second term becomes 4×12log3(x)=2log3(x)4 \times \frac{1}{2} \log_3 (x) = 2 \log_3 (x)
  • The third term: log3(x1/2)=12log3(x)\log_3 (x^{1/2}) = \frac{1}{2} \log_3 (x), so 5×13×12log3(x)=56log3(x)5 \times \frac{1}{3} \times \frac{1}{2} \log_3 (x) = \frac{5}{6} \log_3 (x)

Thus, the equation now is: 3log3(x)2log3(x)56log3(x)=12log3(4)3 \log_3 (x) - 2 \log_3 (x) - \frac{5}{6} \log_3 (x) = \frac{1}{2} \log_3 (4)

Step 3: Combine logarithmic terms

On the left-hand side, combine like terms: (3256)log3(x)=12log3(4)(3 - 2 - \frac{5}{6}) \log_3 (x) = \frac{1}{2} \log_3 (4) (6656)log3(x)=12log3(4)\left( \frac{6}{6} - \frac{5}{6} \right) \log_3 (x) = \frac{1}{2} \log_3 (4) 16log3(x)=12log3(4)\frac{1}{6} \log_3 (x) = \frac{1}{2} \log_3 (4)

Step 4: Solve for log3(x)\log_3 (x)

Multiply both sides by 6 to isolate log3(x)\log_3 (x): log3(x)=3log3(4)\log_3 (x) = 3 \log_3 (4) Thus, x=43=64x = 4^3 = 64.

Final Answer:

The solution is x=64x = 64.

Would you like more details on any step or another explanation?

Here are some related questions you might consider:

  1. How does the change of base formula work for logarithms?
  2. What are the properties of logarithms used in simplification?
  3. How can we apply logarithms to solve exponential equations?
  4. What happens if you solve this equation in terms of a different base, like 10 or e?
  5. How do logarithmic identities assist in solving complex logarithmic expressions?

Tip: Always check that the argument of a logarithm is positive, as logarithms are undefined for non-positive numbers.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Change of Base Formula
Algebra

Formulas

Change of Base Formula: log_b(a) = log_c(a) / log_c(b)
Logarithmic Properties: log_b(a^n) = n * log_b(a)

Theorems

Change of Base Theorem
Properties of Logarithms: Power Rule, Product Rule

Suitable Grade Level

Grades 10-12