Math Problem Statement

Use the properties of logarithms to expand the expression as a sum, difference, and/or constant multiple of logarithms. (Assume the variable is positive.) lnx21x7,>1\ln\frac{x^2-1}{x^7},>1

Solution

To expand the expression lnx21x7\ln \frac{x^2 - 1}{x^7} using the properties of logarithms, follow these steps:

  1. Use the Quotient Rule of Logarithms: The rule states that lnAB=lnAlnB.\ln \frac{A}{B} = \ln A - \ln B. Applying this to our expression: lnx21x7=ln(x21)ln(x7).\ln \frac{x^2 - 1}{x^7} = \ln(x^2 - 1) - \ln(x^7).

  2. Simplify ln(x7)\ln(x^7) using the Power Rule of Logarithms: The Power Rule states that ln(xk)=kln(x).\ln(x^k) = k \cdot \ln(x). Applying this to ln(x7)\ln(x^7): ln(x7)=7ln(x).\ln(x^7) = 7 \ln(x). Substituting back, we get: ln(x21)ln(x7)=ln(x21)7ln(x).\ln(x^2 - 1) - \ln(x^7) = \ln(x^2 - 1) - 7 \ln(x).

  3. Further Expand ln(x21)\ln(x^2 - 1) using the Difference of Squares: Notice that x21=(x+1)(x1).x^2 - 1 = (x + 1)(x - 1). Using the Product Rule of Logarithms, which states that ln(AB)=ln(A)+ln(B)\ln(AB) = \ln(A) + \ln(B), we can expand ln(x21)\ln(x^2 - 1) as follows: ln(x21)=ln((x+1)(x1))=ln(x+1)+ln(x1).\ln(x^2 - 1) = \ln((x + 1)(x - 1)) = \ln(x + 1) + \ln(x - 1).

  4. Combine Everything: Substitute the expanded form of ln(x21)\ln(x^2 - 1) into the expression: lnx21x7=ln(x+1)+ln(x1)7ln(x).\ln \frac{x^2 - 1}{x^7} = \ln(x + 1) + \ln(x - 1) - 7 \ln(x).

Final Answer:

lnx21x7=ln(x+1)+ln(x1)7ln(x).\ln \frac{x^2 - 1}{x^7} = \ln(x + 1) + \ln(x - 1) - 7 \ln(x).

Would you like a deeper explanation of any step?

Here are some related questions:

  1. How does the Power Rule apply to logarithmic expressions?
  2. What are the conditions under which the properties of logarithms apply?
  3. Can this expression be simplified further if additional constraints are known?
  4. How would the answer differ if the base of the logarithm changed from ln\ln to log10\log_{10}?
  5. How can logarithmic properties help in solving exponential equations?

Tip: Always check if an expression can be factored before applying logarithmic properties. Factoring can often make expansions simpler.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Properties of Logarithms
Algebra

Formulas

Quotient Rule: \ln\frac{A}{B} = \ln A - \ln B
Power Rule: \ln(x^k) = k \cdot \ln(x)
Product Rule: \ln(AB) = \ln A + \ln B

Theorems

Quotient Rule of Logarithms
Power Rule of Logarithms
Product Rule of Logarithms

Suitable Grade Level

Grades 9-11