Math Problem Statement

Which graph represents f(x) = log_2 x - 1?

Solution

To identify the correct graph for the function f(x)=log2x1f(x) = \log_2 x - 1, let's analyze its properties:

  1. Basic Shape of Logarithmic Function: The function f(x)=log2xf(x) = \log_2 x has a vertical asymptote at x=0x = 0 and increases as xx increases. The graph generally passes through (1,0)(1, 0) for the function log2x\log_2 x.

  2. Vertical Shift: The subtraction of 1 in f(x)=log2x1f(x) = \log_2 x - 1 results in a vertical downward shift by 1 unit. Therefore, instead of passing through (1,0)(1, 0), it will pass through (1,1)(1, -1).

  3. Key Characteristics:

    • The graph should have a vertical asymptote at x=0x = 0.
    • It should pass through (1,1)(1, -1) due to the downward shift.
    • It should be increasing for x>0x > 0, showing an upward trend as xx moves to the right.

Looking at the four graphs:

  • The top-left graph appears to match these characteristics: it has a vertical asymptote at x=0x = 0, passes through (1,1)(1, -1), and shows an increasing trend as xx increases.

Thus, the correct graph is the top-left option.

Would you like further explanation, or have any questions about logarithmic transformations?

Here are five related questions to deepen your understanding:

  1. How would the graph change if the function were f(x)=log2(x+1)1f(x) = \log_2(x + 1) - 1?
  2. What would happen to the graph if the base of the logarithm changed to a number less than 1, like f(x)=log0.5x1f(x) = \log_{0.5} x - 1?
  3. How does a horizontal shift affect the appearance of logarithmic functions?
  4. What are the domain and range of the function f(x)=log2x1f(x) = \log_2 x - 1?
  5. How can you determine the asymptote of a logarithmic function just by looking at its equation?

Tip: When analyzing transformations, remember that shifts directly added or subtracted from xx affect the graph horizontally, while shifts added or subtracted outside of xx (like 1-1 here) affect it vertically.

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Math Problem Analysis

Mathematical Concepts

Logarithmic Functions
Graph Transformations
Vertical Shifts

Formulas

f(x) = log_2 x - 1

Theorems

Logarithmic Properties
Transformations of Logarithmic Functions

Suitable Grade Level

Grades 10-12