identify the range of the function shown in the graph

2025

3 min read

·

31-03-2025

15

0

Share

Understanding the range of a function is a crucial concept in mathematics. The range represents all possible output values (y-values) of a function. This article will guide you through how to identify the range of a function directly from its graph. We'll cover various function types and approaches to help you master this skill.

What is the Range of a Function?

Before we dive into identifying the range from a graph, let's solidify the definition. The range of a function is the set of all possible output values, or y-values, that the function can produce. It's the complete set of all the values the function can "reach." Think of it as the vertical extent of the function on the coordinate plane.

Identifying the Range from a Graph: Step-by-Step Guide

To determine the range from a graph, follow these steps:

1. Examine the graph: Carefully look at the graph of the function. Pay close attention to the lowest and highest points the graph reaches on the y-axis.

2. Identify the minimum y-value: Find the smallest y-value the graph attains. This might be a specific point or it could approach a value asymptotically (getting closer and closer without actually reaching it).

3. Identify the maximum y-value: Locate the largest y-value the graph reaches. Again, this might be a specific point or an asymptotic value.

4. Determine the interval: Based on the minimum and maximum y-values, express the range as an interval. Use parentheses () for values that are not included (asymptotic values) and square brackets [] for values that are included.

Examples: Identifying the Range of Different Function Types

Let's look at several examples to illustrate how to find the range from graphs of different function types:

Example 1: A Linear Function

(Replace with an actual graph of a linear function, e.g., y = 2x + 1)

Alt Text: Graph of a linear function showing a line that extends infinitely in both directions.

In this case, the line extends infinitely upwards and downwards. Therefore, the range is all real numbers, represented as: (-∞, ∞)

Example 2: A Quadratic Function

(Replace with an actual graph of a parabola)

Alt Text: Graph of a parabola, a U-shaped curve that opens upwards.

Here, the parabola has a minimum y-value at the vertex. Let's assume the vertex is at (2, 1). The parabola extends infinitely upwards. Therefore, the range is: [1, ∞)

Example 3: A Piecewise Function

(Replace with an actual graph of a piecewise function)

Alt Text: Graph of a piecewise function with different segments.

Piecewise functions can have multiple parts. Analyze each piece separately. Determine the minimum and maximum y-values across all pieces to define the overall range. For instance, if the lowest point is at y = -2 and the highest is y = 3, the range would be [-2, 3].

Example 4: An Exponential Function

(Replace with an actual graph of an exponential function)

Alt Text: Graph of an exponential function showing asymptotic behavior.

Exponential functions often have horizontal asymptotes. This means the graph approaches a specific y-value but never actually reaches it. For example, if the asymptote is at y = 0 and the function grows infinitely upwards, the range would be: (0, ∞).

Handling Asymptotes and Discontinuities

When dealing with asymptotes (lines that a graph approaches but doesn't cross) or discontinuities (gaps or breaks in the graph), you need to be extra careful. Asymptotes often define the boundaries of the range. Discontinuities might create gaps in the range interval.

Practice Makes Perfect!

The best way to master identifying the range of a function from its graph is to practice! Work through various examples, paying close attention to the minimum and maximum y-values, the presence of asymptotes, and any discontinuities. Start with simple functions and gradually move towards more complex ones. The more you practice, the more comfortable and confident you'll become.