Math Problem Statement

The graph of y = f(x) is given. Solve the inequalities. Write the solution sets in interval notation.

Solution

The graph of y=f(x)y = f(x) is given, and we are tasked with solving inequalities based on this graph. Specifically, we want to determine where the function f(x)f(x) is positive (above the x-axis) and negative (below the x-axis). The solutions should be written in interval notation.

Step-by-Step Breakdown:

  1. Find the x-intercepts (zeros of the function): These are the points where f(x)=0f(x) = 0, meaning the function crosses the x-axis. From the graph, the approximate x-intercepts are:

    • x=4x = -4
    • x=2x = 2
    • x=5x = 5
  2. Identify intervals where f(x)f(x) is positive or negative:

    • The function is positive where the graph is above the x-axis.
    • The function is negative where the graph is below the x-axis.
  3. Intervals of positivity (f(x)>0f(x) > 0):

    • From x(4,2)x \in (-4, 2), the graph is below the x-axis, so there is no positivity in this region.
    • The function is positive between x=2x = 2 and x=5x = 5, meaning f(x)>0f(x) > 0 on the interval: (2,5)(2, 5)
  4. Intervals of negativity (f(x)<0f(x) < 0):

    • For x(,4)x \in (-\infty, -4), the function is negative (graph is below the x-axis).
    • Between x=4x = -4 and x=2x = 2, the function remains negative.
    • Finally, for x(5,)x \in (5, \infty), the graph again dips below the x-axis.

    So, the function is negative in the intervals: (,4)(4,2)(5,)(-\infty, -4) \cup (-4, 2) \cup (5, \infty)

Solution Sets in Interval Notation:

  • f(x)>0f(x) > 0 on the interval (2,5)(2, 5).
  • f(x)<0f(x) < 0 on the intervals (,4)(4,2)(5,)(-\infty, -4) \cup (-4, 2) \cup (5, \infty).

Do you have any questions about these inequalities or need more details?


Here are 5 related questions that may help you expand your understanding:

  1. How do you determine if a function is positive or negative based solely on its graph?
  2. What happens at the x-intercepts of a function in terms of positivity or negativity?
  3. Can a function have more than one interval where it is positive or negative?
  4. How would the solution change if the graph touched the x-axis but didn’t cross it at certain points?
  5. How would you find the exact values of the x-intercepts algebraically?

Tip: Always pay attention to the behavior of the function around the x-intercepts when solving inequalities; the function switches sign at these points.

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Math Problem Analysis

Mathematical Concepts

Inequalities
Graphs of Functions
X-intercepts

Formulas

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Theorems

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Suitable Grade Level

Grades 9-12