Math Problem Statement

Match the logarithmic function with one of the graphs labeled I or II. f(x) = ln(x − 1)

The x y-coordinate plane with a graph labeled I is given. The curve enters the window almost vertically just to the right of the y-axis, goes up and right becoming less steep, crosses the x-axis at approximately x = 0.37, passes through the marked point (1, 1), and exits the window in the first quadrant.

Solution

To match the logarithmic function f(x)=ln(x1)f(x) = \ln(x - 1) with the given graphs, we need to carefully analyze its properties and compare them to the description of graph II.

Step 1: Key properties of f(x)=ln(x1)f(x) = \ln(x - 1)

  1. Domain: The logarithmic function ln(x1)\ln(x - 1) is defined only for x1>0x - 1 > 0, meaning x>1x > 1. The function has a vertical asymptote at x=1x = 1.
  2. Behavior near x=1x = 1: As x1+x \to 1^+, ln(x1)\ln(x - 1) \to -\infty. The graph approaches the line x=1x = 1 but never touches it.
  3. Intercept: The xx-intercept occurs when ln(x1)=0\ln(x - 1) = 0, which happens when x1=1x - 1 = 1, or x=2x = 2.
  4. Increasing nature: The function is increasing for all x>1x > 1, as the natural logarithm is an increasing function.
  5. Point to check: At x=3x = 3, for example, ln(31)=ln(2)0.693\ln(3 - 1) = \ln(2) \approx 0.693.

Step 2: Analyze graph II

  1. Graph II enters the window almost vertically to the right of the yy-axis.
  2. It becomes less steep as xx increases and exits the window in the first quadrant.
  3. The graph crosses the xx-axis at approximately x=0.37x = 0.37.
  4. The graph passes through the point (1,1)(1, 1).

Step 3: Match properties with graph II

  • The function f(x)=ln(x1)f(x) = \ln(x - 1) is undefined for x1x \leq 1, so it cannot pass through (1,1)(1, 1), making graph II inconsistent with the given function.

Step 4: Conclusion

The function f(x)=ln(x1)f(x) = \ln(x - 1) does not match graph I because graph II suggests a logarithmic function of the form ln(x+c)\ln(x + c) where c>0c > 0, or another shifted logarithmic function.

Would you like a detailed explanation of why f(x)f(x) aligns with another type of graph, or have any specific follow-ups?

Questions:

  1. What transformations occur if the logarithmic function is shifted horizontally?
  2. How does the domain of logarithmic functions affect their graph?
  3. Can you describe the significance of the vertical asymptote in logarithmic functions?
  4. How does the behavior near the asymptote differ for ln(xc)\ln(x - c) versus ln(cx)\ln(c - x)?
  5. What is the role of the xx-intercept in identifying the correct logarithmic graph?

Tip:

Always check the domain and intercepts of a logarithmic function before attempting to match it to a graph!

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Math Problem Analysis

Mathematical Concepts

Logarithmic Functions
Transformations of Functions
Graphing Functions

Formulas

f(x) = ln(x - 1)

Theorems

Domain of logarithmic functions
Vertical asymptote of logarithmic functions

Suitable Grade Level

Grades 9-12