Math Problem Statement

If log10x – log10√x = 2 logx10, then solve for x:

Solution

Let's solve the equation given:

log10xlog10x=2logx10\log_{10} x - \log_{10} \sqrt{x} = 2 \log_x 10

First, let's simplify the left-hand side of the equation using logarithmic properties.

Recall that log10x=log10x1/2=12log10x\log_{10} \sqrt{x} = \log_{10} x^{1/2} = \frac{1}{2} \log_{10} x. Therefore:

log10x12log10x=12log10x\log_{10} x - \frac{1}{2} \log_{10} x = \frac{1}{2} \log_{10} x

The left-hand side simplifies to:

12log10x\frac{1}{2} \log_{10} x

So the equation now is:

12log10x=2logx10\frac{1}{2} \log_{10} x = 2 \log_x 10

Next, we use the change of base formula for logarithms. Recall that:

logx10=log1010log10x\log_x 10 = \frac{\log_{10} 10}{\log_{10} x}

Since log1010=1\log_{10} 10 = 1, we have:

logx10=1log10x\log_x 10 = \frac{1}{\log_{10} x}

Thus, the equation becomes:

12log10x=21log10x\frac{1}{2} \log_{10} x = 2 \cdot \frac{1}{\log_{10} x}

Multiplying both sides by log10x\log_{10} x to eliminate the fraction:

12(log10x)2=2\frac{1}{2} (\log_{10} x)^2 = 2

To isolate (log10x)2(\log_{10} x)^2, multiply both sides by 2:

(log10x)2=4(\log_{10} x)^2 = 4

Now, take the square root of both sides:

log10x=±2\log_{10} x = \pm 2

This gives us two cases:

  1. log10x=2\log_{10} x = 2
  2. log10x=2\log_{10} x = -2

For the first case:

log10x=2    x=102=100\log_{10} x = 2 \implies x = 10^2 = 100

For the second case:

log10x=2    x=102=0.01\log_{10} x = -2 \implies x = 10^{-2} = 0.01

Therefore, the solutions for xx are:

100 and 0.01\boxed{100 \text{ and } 0.01}

Would you like further details on this explanation, or do you have any questions? Here are some related questions for practice:

  1. If log10(2x)log10x=1\log_{10} (2x) - \log_{10} x = 1, what is the value of xx?
  2. Solve for xx if log10(x2)log10(x)=log10(x3)log10(x2)\log_{10} (x^2) - \log_{10} (x) = \log_{10} (x^3) - \log_{10} (x^2).
  3. If log10x+log10(x+1)=1\log_{10} x + \log_{10} (x + 1) = 1, what is the value of xx?
  4. Solve for xx if 3log10x=2log1053 \log_{10} x = 2 \log_{10} 5.
  5. What is the value of xx if log10(5x)=log10(25)2\log_{10} (5x) = \log_{10} (25) - 2?
  6. If log10x=13log1027\log_{10} x = \frac{1}{3} \log_{10} 27, what is the value of xx?
  7. Solve for xx if log10(x+3)log10x=1\log_{10} (x + 3) - \log_{10} x = 1.
  8. What is the value of xx if log10(x2+3x)=log10(x2)+log10(3x)\log_{10} (x^2 + 3x) = \log_{10} (x^2) + \log_{10} (3x)?

Tip: Remember that logarithmic equations often require properties such as the change of base formula, the power rule, and the product or quotient rules for simplification.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Change of base formula

Formulas

Logarithm properties

Theorems

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Suitable Grade Level

High School