Math Problem Statement

Use rules of logarithms to expand \( \ln(\sqrt{7xy}) \).

Solution

Let's expand the expression step-by-step to solve it correctly.

The original expression is:

ln(7xy)\ln\left(\sqrt{7xy}\right)

Step 1: Use the Square Root Property

Rewrite the square root as a fractional exponent: ln(7xy)=ln((7xy)12)\ln\left(\sqrt{7xy}\right) = \ln\left((7xy)^{\frac{1}{2}}\right)

Step 2: Apply the Power Rule for Logarithms

The power rule for logarithms states that ln(ab)=bln(a)\ln(a^b) = b \cdot \ln(a). So: ln((7xy)12)=12ln(7xy)\ln\left((7xy)^{\frac{1}{2}}\right) = \frac{1}{2} \cdot \ln(7xy)

Step 3: Expand ln(7xy)\ln(7xy) Using the Product Rule

The product rule for logarithms states that ln(abc)=ln(a)+ln(b)+ln(c)\ln(abc) = \ln(a) + \ln(b) + \ln(c). Apply this to ln(7xy)\ln(7xy): ln(7xy)=ln(7)+ln(x)+ln(y)\ln(7xy) = \ln(7) + \ln(x) + \ln(y)

Step 4: Substitute and Simplify

Now, substitute back: 12(ln(7)+ln(x)+ln(y))\frac{1}{2} \cdot \left(\ln(7) + \ln(x) + \ln(y)\right)

Distribute the 12\frac{1}{2}: =12ln(7)+12ln(x)+12ln(y)= \frac{1}{2} \ln(7) + \frac{1}{2} \ln(x) + \frac{1}{2} \ln(y)

Final Answer

This matches the correct choice: 12ln(7)+12ln(x)+12ln(y)\frac{1}{2} \ln(7) + \frac{1}{2} \ln(x) + \frac{1}{2} \ln(y)

This answer corresponds to the option:

  • Option 2: 12[ln(7)+ln(x)+ln(y)]\frac{1}{2} [\ln(7) + \ln(x) + \ln(y)]

Would you like more details on any of these steps?


Here are some questions to further your understanding:

  1. What is the difference between the product rule and the power rule for logarithms?
  2. How would the steps change if it were ln(7x/y)\ln(\sqrt{7x/y}) instead?
  3. Why is it important to distribute the 12\frac{1}{2} across all terms in the logarithm?
  4. How can the properties of logarithms help simplify complex expressions?
  5. What is the effect of changing the base of the logarithm on this problem?

Tip: Always break down composite functions (like roots and products) into simpler parts using the rules of logarithms to make problems easier to handle.

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Math Problem Analysis

Mathematical Concepts

Logarithmic Expansion
Algebra

Formulas

Power Rule for Logarithms: \( \ln(a^b) = b \cdot \ln(a) \)
Product Rule for Logarithms: \( \ln(abc) = \ln(a) + \ln(b) + \ln(c) \)

Theorems

Logarithmic Properties

Suitable Grade Level

Grades 10-12