Math Problem Statement

(2log_3 x - 4) / log_3(x/9) = log_3(x^7) - (1 / log_3 3)^2 - 8. Find the lowest value of X.

Solution

The equation in the image appears to be:

2log3x4log3(x9)=log3(x7)(1log33)28\frac{2 \log_3 x - 4}{\log_3 \left( \frac{x}{9} \right)} = \log_3 \left( x^7 \right) - \left( \frac{1}{\log_3 3} \right)^2 - 8

We are tasked with finding the lowest value of xx.

Let me break down the equation and solve it step by step.

  1. Simplify the logarithmic expressions:

    • log3(x7)=7log3(x)\log_3(x^7) = 7 \log_3(x).
    • log3(x9)=log3(x)log3(9)=log3(x)2\log_3 \left( \frac{x}{9} \right) = \log_3(x) - \log_3(9) = \log_3(x) - 2, since log3(9)=2\log_3(9) = 2.
    • 1log3(3)=1\frac{1}{\log_3(3)} = 1, since log3(3)=1\log_3(3) = 1, so (1log3(3))2=12=1\left( \frac{1}{\log_3(3)} \right)^2 = 1^2 = 1.
  2. Substitute into the equation: 2log3x4log3x2=7log3x18\frac{2 \log_3 x - 4}{\log_3 x - 2} = 7 \log_3 x - 1 - 8 Simplifying further: 2log3x4log3x2=7log3x9\frac{2 \log_3 x - 4}{\log_3 x - 2} = 7 \log_3 x - 9

  3. Multiply both sides by log3x2\log_3 x - 2 to eliminate the denominator: 2log3x4=(7log3x9)(log3x2)2 \log_3 x - 4 = (7 \log_3 x - 9)(\log_3 x - 2) Expand the right-hand side: 2log3x4=7(log3x)214log3x9log3x+182 \log_3 x - 4 = 7 (\log_3 x)^2 - 14 \log_3 x - 9 \log_3 x + 18 Simplifying the right-hand side: 2log3x4=7(log3x)223log3x+182 \log_3 x - 4 = 7 (\log_3 x)^2 - 23 \log_3 x + 18

  4. Move all terms to one side: 0=7(log3x)225log3x+220 = 7 (\log_3 x)^2 - 25 \log_3 x + 22

This is a quadratic equation in terms of log3x\log_3 x. Now, I will solve this quadratic equation using the quadratic formula:

log3x=(25)±(25)2472227\log_3 x = \frac{-(-25) \pm \sqrt{(-25)^2 - 4 \cdot 7 \cdot 22}}{2 \cdot 7}

Let me calculate this next.The solutions for log3x\log_3 x are:

log3x=2orlog3x=1.5714\log_3 x = 2 \quad \text{or} \quad \log_3 x = 1.5714

To find xx, we take the inverse logarithm (base 3) of both values:

  • If log3x=2\log_3 x = 2, then x=32=9x = 3^2 = 9.
  • If log3x=1.5714\log_3 x = 1.5714, then x31.57144.99x \approx 3^{1.5714} \approx 4.99.

Thus, the lowest value of xx is approximately 4.99.

Would you like more details or further clarification?

Here are 5 related questions for further exploration:

  1. How does the change of base formula for logarithms work?
  2. What are common properties of logarithmic equations?
  3. How can the quadratic formula be derived from a general quadratic equation?
  4. Can logarithmic equations have multiple solutions?
  5. What are real-world applications of logarithms in various fields?

Tip: When solving logarithmic equations, always check if the solutions fall within the domain of the logarithmic function.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Logarithms
Quadratic Equations
Algebra

Formulas

log_3(x^7) = 7 * log_3(x)
log_3(x/9) = log_3(x) - log_3(9) = log_3(x) - 2
Quadratic formula: (-b ± √(b^2 - 4ac)) / 2a

Theorems

Properties of Logarithms
Quadratic Formula

Suitable Grade Level

Grades 10-12