Range Examples in Math

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Range.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Math.

Concept Recap

The range of a function is the set of all actual output values that the function can produce for inputs in its domain.

The range is the set of all possible "answers" the function can give β€” some output values may be unreachable no matter what valid input you choose.

Read the full concept explanation β†’

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Range is what the function actually produces, not what's theoretically possible.

Common stuck point: Range is often harder to find than domainβ€”may need graphing.

Sense of Study hint: Sketch the graph or make a table of outputs for several inputs, then look for the lowest and highest y-values the function actually reaches.

Worked Examples

Example 1

easy
Find the range of f(x) = x^2 + 1.

Solution

  1. 1
    Since x^2 \geq 0 for all real x, the minimum value of x^2 is 0.
  2. 2
    Therefore f(x) = x^2 + 1 \geq 0 + 1 = 1.
  3. 3
    As x \to \pm\infty, f(x) \to \infty, so the range is [1, \infty).

Answer

[1, \infty)
For quadratics f(x) = ax^2 + bx + c with a > 0, the minimum value occurs at the vertex. Adding a constant shifts the range upward.

Example 2

medium
Find the range of g(x) = \frac{2x + 1}{x - 3} for x \neq 3.

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

easy
Find the range of f(x) = -|x| + 4.

Example 2

hard
Find the range of f(x) = \frac{x^2 - 4}{x^2 + 1}.

Related Concepts

Background Knowledge

These ideas may be useful before you work through the harder examples.

function definitiondomain