Math Problem Statement

Explain how the graph of the function f(x) = 1/(x+4) can be obtained from the graph of y = 1/x. Then graph f and give the (a) domain and (b) range. Determine the largest open intervals of the domain over which the function is (c) increasing or (d) decreasing.

Solution

To solve the problem, we need to analyze how the graph of f(x)=1x+4f(x) = \frac{1}{x+4} can be obtained from the graph of y=1xy = \frac{1}{x}, and also to discuss the domain, range, and intervals of increase and decrease.

Step-by-Step Solution:

  1. Transformation:

    • The given function is f(x)=1x+4f(x) = \frac{1}{x+4}.
    • This is a horizontal shift of the basic function y=1xy = \frac{1}{x}.
    • To transform y=1xy = \frac{1}{x} into f(x)=1x+4f(x) = \frac{1}{x+4}, we shift the graph 4 units to the left.
    • Therefore, to obtain the graph of ff, shift the graph of y=1xy = \frac{1}{x} 4 units to the left.
  2. Graphing:

    • The basic graph of y=1xy = \frac{1}{x} has vertical asymptote at x=0x = 0 and horizontal asymptote at y=0y = 0.
    • After shifting 4 units to the left, the vertical asymptote of f(x)=1x+4f(x) = \frac{1}{x+4} will be at x=4x = -4, and the horizontal asymptote will remain at y=0y = 0.
  3. Domain:

    • The domain of y=1xy = \frac{1}{x} is all real numbers except x=0x = 0.
    • For f(x)=1x+4f(x) = \frac{1}{x+4}, the domain is all real numbers except x=4x = -4.
    • Hence, the domain of ff is (,4)(4,)(-\infty, -4) \cup (-4, \infty).
  4. Range:

    • The range of y=1xy = \frac{1}{x} is all real numbers except y=0y = 0.
    • Similarly, for f(x)=1x+4f(x) = \frac{1}{x+4}, the range remains all real numbers except y=0y = 0.
    • Hence, the range of ff is (,0)(0,)(-\infty, 0) \cup (0, \infty).
  5. Intervals of Increase and Decrease:

    • The function y=1xy = \frac{1}{x} decreases on (,0)(-\infty, 0) and increases on (0,)(0, \infty).
    • After the horizontal shift, f(x)=1x+4f(x) = \frac{1}{x+4} will decrease on (,4)(-\infty, -4) and increase on (4,)(-4, \infty).

Summary:

  • To obtain the graph of ff, shift the graph of y=1xy = \frac{1}{x} 4 units to the left.
  • Domain: (,4)(4,)(-\infty, -4) \cup (-4, \infty)
  • Range: (,0)(0,)(-\infty, 0) \cup (0, \infty)
  • Intervals of Decrease: (,4)(-\infty, -4)
  • Intervals of Increase: (4,)(-4, \infty)

Would you like more details or have any questions about this solution?

Here are five related questions to expand your understanding:

  1. How would the graph change if we had f(x)=1x4f(x) = \frac{1}{x-4}?
  2. What are the horizontal and vertical asymptotes of the function g(x)=1x3g(x) = \frac{1}{x-3}?
  3. How do you find the domain of a rational function?
  4. What is the effect of a vertical shift on the graph of y=1xy = \frac{1}{x}?
  5. How do you determine the intervals where a function is increasing or decreasing?

Tip: When analyzing transformations of functions, always identify the basic function and apply the transformations step-by-step (shifts, stretches, reflections, etc.).

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Rational Functions
Graph Transformations
Domain and Range
Asymptotes
Increasing and Decreasing Intervals

Formulas

Transformation of rational functions
Domain of rational functions
Range of rational functions

Theorems

Horizontal Shift Theorem
Behavior of Rational Functions Near Asymptotes

Suitable Grade Level

Grades 10-12