Skip to main content
Ch. 2 - Graphs and Functions
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 3, Problem 21

Graph each piecewise-defined function.
f(x)={x1if x32if x>3f(x) =\(\begin{cases}\)x - 1 & \(\text{if }\) x \(\leq\) 3 \\2 & \(\text{if }\) x > 3\(\end{cases}\)

Verified step by step guidance
1
Step 1: Understand the piecewise function definition. The function f(x) is defined as two different expressions depending on the value of x: for x ≤ 1, f(x) = x + 4; for x > 1, f(x) = 5.
Step 2: Graph the first piece, f(x) = x + 4 for x ≤ 1. This is a linear function with slope 1 and y-intercept 4. Plot points for values of x less than or equal to 1, such as x = 0, x = 1, and connect them with a straight line extending to the left.
Step 3: Determine the point at x = 1 for the first piece. Calculate f(1) = 1 + 4 = 5. This point (1, 5) will be included in the graph of the first piece because the inequality is 'less than or equal to'.
Step 4: Graph the second piece, f(x) = 5 for x > 1. This is a constant function, so draw a horizontal line at y = 5 for all x values greater than 1. Use an open circle at (1, 5) if you want to indicate that this piece does not include x = 1, but since the first piece includes x = 1, the point at (1, 5) belongs to the first piece.
Step 5: Combine both pieces on the same coordinate plane. The graph will show a line with slope 1 up to and including x = 1, and a horizontal line at y = 5 for x values greater than 1. This completes the graph of the piecewise function.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
4m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Piecewise-Defined Functions

A piecewise-defined function is a function composed of different expressions depending on the input value's domain. Each piece applies to a specific interval, and the function's value changes according to these conditions. Understanding how to interpret and graph each piece separately is essential.
Recommended video:
3:51
Domain Restrictions of Composed Functions

Graphing Functions with Domain Restrictions

When graphing piecewise functions, it is important to restrict each part of the function to its specified domain. This means plotting the function only where the condition (like x ≤ 1 or x > 1) holds true, and using open or closed points to indicate whether endpoints are included or excluded.
Recommended video:
3:51
Domain Restrictions of Composed Functions

Continuity and Discontinuity in Piecewise Functions

Piecewise functions may be continuous or have jumps at the points where the pieces meet. Checking the function values at boundary points helps determine if the graph connects smoothly or has a break, which affects the overall shape and interpretation of the function.
Recommended video:
3:34
Determining Removable Discontinuities (Holes)