Increasing and Decreasing Function Intervals Practice

Master identifying increasing and decreasing intervals of functions with step-by-step practice problems, graphical analysis, and real-world applications.

📚What You'll Master in This Practice Session
  • Identify increasing intervals where function values grow as x increases
  • Locate decreasing intervals where function values fall with increasing x
  • Analyze function graphs to determine interval notation for increasing/decreasing regions
  • Connect minimum and maximum points to interval boundaries
  • Apply interval concepts to real-world situations and word problems
  • Use proper mathematical notation to express increasing and decreasing intervals

Understanding Increasing Intervals of a function

Complete explanation with examples

The increasing intervals of a function

An increasing interval of a function expresses the same values of X (the interval), in which the values of the function (Y) grow parallel to the growth of the values of X to the right.

In certain cases, the increasing interval begins at the minimum point, but it does not necessarily have to be this way.

Detailed explanation

Practice Increasing Intervals of a function

Test your knowledge with 17 quizzes

Determine the domain of the following function:

A function describing the charging of a computer battery during use.

Examples with solutions for Increasing Intervals of a function

Step-by-step solutions included
Exercise #1

Is the function shown in the graph below decreasing?

yx

Step-by-Step Solution

The graph presented is a straight line. To determine whether the function is decreasing, we need to examine the slope of this line.

The line has a negative slope, as it moves downward from left to right. A function is considered decreasing when its slope is negative.

In formal terms, for a linear function expressed as y=mx+c y = mx + c , if the slope m m is negative, the function is decreasing over its entire domain.

From the graph, it's evident that the line has a negative slope, thus indicating that the function is indeed decreasing.

Therefore, the answer to the problem is Yes.

Answer:

Yes

Exercise #2

Is the function in the graph decreasing?

yx

Step-by-Step Solution

To analyze whether the function in the graph is decreasing, we must understand how the function's behavior is defined by its graph:

  • Step 1: Examine the graph. The graph presented is a horizontal line.
  • Step 2: Recognize the properties of a horizontal line. Horizontally aligned lines correspond to constant functions because the y y -value remains the same for all x x -values.
  • Step 3: Define the criteria for a function to be decreasing. A function decreases when, as x x increases, the value of f(x) f(x) decreases.
  • Step 4: Apply this criterion to the horizontal line. Since the y y -value is constant and does not decrease as x x moves rightward, the function is not decreasing.

Therefore, the function represented by the graph is not decreasing.

Answer:

No

Exercise #3

Is the function in the graph below decreasing?

yx

Step-by-Step Solution

To determine if the function is decreasing, we will analyze the graph visually:

The graph shows a line connecting from the bottom-left to the top-right of the graph area, indicating the line has a positive slope. This type of graph indicates the function is increasing, not decreasing.

A decreasing function means its value goes down as x x increases, which is equivalent to having a negative slope.

Since the graph appears with a positive slope, the function is not decreasing.

Thus, the correct choice to the problem, which asks if the function in the graph is decreasing, is No.

Answer:

No

Exercise #4

Does the function in the graph decrease throughout?

YYYXXX

Step-by-Step Solution

To solve this problem, we'll begin by examining the graph of the function provided:

  • Step 1: Observe the graph from left to right along the x-axis.
  • Step 2: Look for any intervals where the function value (y-coordinate) does not decrease as the x-value increases.
  • Step 3: Pay special attention to segments where the graph might look horizontal or rising.

Upon inspecting the graph, we find:

- There are sections where the function's y-values appear to remain constant or potentially rise as the x-values increase. Specifically, even if the function decreases in major portions, any interval where it doesn't means the function cannot be classified as decreasing throughout.

Thus, the function does not strictly decrease on the entire interval shown. Therefore, the solution to the problem is No.

Answer:

No

Exercise #5

Is the function in the graph decreasing? yx

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Verify the graph's overall path direction
  • Step 2: Confirm if the y-values are decreasing as we proceed from the left side of the graph to the right side (increasing x-values).

Now, let's work through each step:

Step 1: By examining the graph, the red line starts at a higher point on the y-axis and moves downward to a lower point as it moves horizontally across the x-axis from left to right.

Step 2: Since for every point, the red line descends as it progresses from the leftmost point to the rightmost, this indicates a consistent decrease in the y-values.

Therefore, the solution to the problem is Yes, the function in the graph is decreasing.

Answer:

Yes

Frequently Asked Questions

What is an increasing interval of a function?

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An increasing interval is a range of x-values where the function values (y) grow as x increases to the right. On a graph, this appears as the function rising from left to right in that interval.

How do you find increasing and decreasing intervals on a graph?

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To find intervals: 1) Look at the graph from left to right, 2) Mark where the function rises (increasing) or falls (decreasing), 3) Write intervals using proper notation like (a,b) or [a,b].

Do increasing intervals always start at minimum points?

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No, increasing intervals don't necessarily begin at minimum points. While they often do, an increasing interval can start at any point where the function begins to rise.

What's the difference between increasing and decreasing function intervals?

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Increasing intervals show function values rising as x increases (upward slope). Decreasing intervals show function values falling as x increases (downward slope).

How do you write interval notation for increasing functions?

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Use parentheses ( ) for open intervals and brackets [ ] for closed intervals. For example: increasing on (2,5) means from x=2 to x=5, not including endpoints.

Can a function be both increasing and decreasing?

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Yes, most functions have different intervals where they increase and decrease. The function changes behavior at turning points like maximums and minimums.

What are real-world examples of increasing and decreasing intervals?

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Examples include: population growth over time (increasing), temperature throughout a day (both increasing and decreasing), or profit vs. production cost relationships in business.

How do maximum and minimum points relate to function intervals?

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Maximum points often mark the end of increasing intervals and start of decreasing intervals. Minimum points typically end decreasing intervals and begin increasing intervals.

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