Math Problem Statement

log10(x10(x + 5) = 1 + log10 2 give your answer in exact form

Solution

To solve the equation:

log10(x10(x+5))=1+log10(2),\log_{10}(x10(x + 5)) = 1 + \log_{10}(2),

follow these steps:

Step 1: Simplify the left-hand side

Using the property of logarithms log10(ab)=log10(a)+log10(b)\log_{10}(ab) = \log_{10}(a) + \log_{10}(b), rewrite the left-hand side: log10(x10(x+5))=log10(x)+log10(10)+log10(x+5).\log_{10}(x10(x + 5)) = \log_{10}(x) + \log_{10}(10) + \log_{10}(x + 5).

Since log10(10)=1\log_{10}(10) = 1, this becomes: log10(x10(x+5))=log10(x)+1+log10(x+5).\log_{10}(x10(x + 5)) = \log_{10}(x) + 1 + \log_{10}(x + 5).

Step 2: Set up the equation

Substituting back into the original equation: log10(x)+1+log10(x+5)=1+log10(2).\log_{10}(x) + 1 + \log_{10}(x + 5) = 1 + \log_{10}(2).

Cancel 11 from both sides: log10(x)+log10(x+5)=log10(2).\log_{10}(x) + \log_{10}(x + 5) = \log_{10}(2).

Step 3: Combine logarithmic terms

Using the property log10(a)+log10(b)=log10(ab)\log_{10}(a) + \log_{10}(b) = \log_{10}(ab), combine the terms: log10(x(x+5))=log10(2).\log_{10}(x(x + 5)) = \log_{10}(2).

Step 4: Exponentiate to remove the logarithm

Exponentiating both sides with base 10: x(x+5)=2.x(x + 5) = 2.

Step 5: Solve the quadratic equation

Expand and simplify: x2+5x2=0.x^2 + 5x - 2 = 0.

Use the quadratic formula: x=b±b24ac2a,x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}, where a=1a = 1, b=5b = 5, c=2c = -2. Substituting: x=5±524(1)(2)2(1)=5±25+82=5±332.x = \frac{-5 \pm \sqrt{5^2 - 4(1)(-2)}}{2(1)} = \frac{-5 \pm \sqrt{25 + 8}}{2} = \frac{-5 \pm \sqrt{33}}{2}.

Step 6: Consider only valid solutions

Since x>0x > 0 (logarithms are undefined for non-positive values), the solution is: x=5+332.x = \frac{-5 + \sqrt{33}}{2}.

Final Answer:

x=5+332.x = \frac{-5 + \sqrt{33}}{2}.

Would you like a detailed breakdown of any step or further assistance?

Questions:

  1. How does the quadratic formula work in other contexts?
  2. Why can logarithms only accept positive arguments?
  3. How does combining logarithms simplify expressions?
  4. What happens if no real solutions exist in a logarithmic equation?
  5. How can we interpret this solution geometrically?

Tip:

When solving logarithmic equations, always check if the solution satisfies the domain of the logarithm (positive arguments only).

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Math Problem Analysis

Mathematical Concepts

Logarithms
Algebra
Quadratic Equations

Formulas

log10(ab) = log10(a) + log10(b)
log10(a) - log10(b) = log10(a/b)
Quadratic formula: x = (-b ± sqrt(b^2 - 4ac)) / 2a

Theorems

Properties of Logarithms
Quadratic Formula

Suitable Grade Level

Grades 10-12