Math Problem Statement

Use the definition of the logarithmic function to find x. (Simplify your answers completely.)

(a)

logx(8) =

1

2

x =

(b)

logx(5) =

1

3

x =

Solution

To solve these logarithmic equations, we will rewrite each equation in exponential form, using the property:

logb(a)=c    bc=a\log_b(a) = c \implies b^c = a

(a) logx(8)=12\log_x(8) = \frac{1}{2}

Using the definition:

x12=8x^{\frac{1}{2}} = 8

This simplifies to:

x=8\sqrt{x} = 8

Squaring both sides:

x=82=64x = 8^2 = 64

So, the solution is:

x=64x = 64


(b) logx(5)=13\log_x(5) = \frac{1}{3}

Using the definition:

x13=5x^{\frac{1}{3}} = 5

This simplifies to:

x3=5\sqrt[3]{x} = 5

Cubing both sides:

x=53=125x = 5^3 = 125

So, the solution is:

x=125x = 125


Final Answers:

(a) x=64x = 64
(b) x=125x = 125

Let me know if you'd like further explanations!


Here are some related questions to expand your understanding:

  1. How does the definition of logarithms help rewrite exponential equations?
  2. Can you verify the solutions x=64x = 64 and x=125x = 125 by substitution?
  3. What is the meaning of fractional powers like 12\frac{1}{2} and 13\frac{1}{3} in terms of roots?
  4. How would the solutions change if the bases of the logarithms were different?
  5. Can you think of real-life applications where solving logarithmic equations is useful?

Tip: Always confirm logarithmic solutions by substituting them back into the original equation to verify correctness.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Exponential Equations
Fractional Exponents

Formulas

log_b(a) = c implies b^c = a
x^(1/n) = a implies x = a^n

Theorems

Definition of Logarithmic Function

Suitable Grade Level

Grades 9-12

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