The range of a function is the collection of numbers (or set) containing all the function's outputs.

Consider the function f(x), defined by the mapping diagram below.

In a mapping diagram, the range consists of all the outputs to which an arrow is drawn. Therefore, the range is

\{ -1,2,3 \}.

The value y=0 is not part of the range because there is no x -value such that f(x) = 0.

FLAG

What is the range of the function g defined by the mapping diagram shown below?

EXPLANATION

The range of g(x) consists of all the outputs that have a corresponding x -input.

In a mapping diagram, the range consists of all the outputs to which an arrow is drawn.

Therefore, the range is the set \{ 3,6,9,12 \}.

FLAG

What is the range of the function $g$ defined by the mapping diagram shown above?

a
$(2,10]$
b
$\{ 4,6,8,10 \}$
c
$\{ 0,4,6,8,10 \}$
d
$ [4,10]$
e
$(-\infty,\infty)$

What is the range of the function $f$ defined by the mapping diagram shown above?

a
$[1, 4]$
b
$[0,4]$
c
$ \{0, 2, 1, 4 \}$
d
$[1, \infty]$
e
$ \{1, 2, 4 \}$

What is the range of the function f defined by the following table?

x -3 -2 -1 0 1 2 3
f(x) -1 4 3 -1 4 2 0
EXPLANATION

The range of f(x) consists of all the outputs that have a corresponding x -input.

In a table, the range consists of all numbers that feature in the row corresponding to f(x).

Therefore, the range is the set \{ -1,0,2,3,4 \}.

FLAG

What is the range of the function $f$ defined by the following table?

$x$ $-3$ $-2$ $-1$ $0$ $1$ $2$
$f(x)$ $0$ $-3$ $1$ $2$ $-1$ $4$
a
$\{0,1,2,4 \}$
b
$\{-3,-1,0,1,2,4 \}$
c
$[-3,4]$
d
$[-3,2]$
e
$\{-3,-2,-1,0,1,2 \}$

What is the range of the function $h$ defined by the following table?

$x$ $0$ $1$ $-2$ $3$ $-4$ $5$ $-6$ $7$
$h(x)$ $-7$ $6$ $-5$ $4$ $-3$ $6$ $-1$ $0$
a
$( -7, 0 )$
b
$[ -7, 6 ]$
c
$\{ -7, -5, -3, -1, 0, 4, 6 \}$
d
$\{ -7, 0 \}$
e
$\{ -7, -5, -3, -1, 0, 2, 4, 6 \}$

When we graph a function, the range is the set of all y -values given by the graph.

For example, consider the linear function f(x) = 2x, graphed below.

The graph covers all y -values, so the range of the function is

-\infty < y< \infty,

which we can also write as -\infty < f(x) < \infty.

Furthermore, we can express the range as f(x)\in (-\infty,\infty) using interval notation.

If we restrict the domain, the range also changes. Let's now consider the function g(x) = 2x, \quad x \in [0,2).

The graph y = g(x) is shown below.

The y values go from y=0 up to (but not including) y=4, including every value in between. Therefore, the range of the function is

0\leq g(x) < 4.

Using interval notation, we can also write the range as g(x)\in [0,4).

FLAG

What is the range of the function f(x) defined by the graph below?

EXPLANATION

First, we find the lowest and highest y -values in the graph.

  • The lowest y -value is -1. This occurs at the point (-1,-1).

  • The highest y -value is 8. This occurs at the point (2,8).

The function covers all the y -values between -1 and 8, including both -1 and 8.

Therefore, the range is

-1\leq y \leq 8,

which can also be written as

-1\leq f(x) \leq 8.

FLAG

What is the range of the function $f(x),$ shown above?

a
$-1 \leq f(x)\leq 1$
b
$-4 \lt f(x)\lt 4$
c
$-4 \leq f(x)\leq 4$
d
$-1 \leq f(x)\leq 0$
e
$-1 \leq f(x)\lt 1$

What is the range of the function $f(x),$ shown above?

a
$-1 \lt f(x) \lt 3$
b
$-1 \leq f(x) \leq 3$
c
$-3 \leq f(x) \leq 1$
d
$0 \lt f(x) \leq 3$
e
$-3 \lt f(x) \lt 1$
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