Domain, Codomain and Range

Rarely Tested

Domain, Codomain and Range

## Formula

For:

$$f:A\to B$$

$$\text{Domain}(f)=A$$

$$\text{Codomain}(f)=B$$

$$\text{Range}(f)=f(A)\subseteq B$$

## Conditions / Special Cases

In general:

$$\text{Range}(f)\ne\text{Codomain}(f)$$

For an onto function:

$$\text{Range}(f)=\text{Codomain}(f)$$

## Usage

- Used to determine whether a function is onto.

- Essential when finding domains and ranges of functions.

Question 1

If the domain of the function $$f(x)=\log_{(10x^{2}-17x+7)}{(18x^{2}-11x+1)}$$ is $$(-\infty ,a)\cup (b,c)\cup (d,\infty)-{e}$$ and 90(a + b + c + d + e) equals:

Question 2

If the domain of the function $$f(x) = \log_x(1 - \log_4(x^2 - 9x + 18))$$ is $$(\alpha, \beta) \cup (\gamma, \delta)$$, then $$\alpha + \beta + \gamma + \delta$$ is equal to

Question 3

Let the domain of the function $$f(x) = \cos^{-1}\left(\frac{4x+5}{3x-7}\right)$$ be $$[\alpha, \beta]$$ and the domain of $$g(x) = \log_2(2 - 6\log_{27}(2x+5))$$ be $$(\gamma, \delta)$$. Then $$|7(\alpha + \beta) + 4(\gamma + \delta)|$$ is equal to _____.

Log in to view all questions

Go back to topics

Join CAT 2026 course by 5-Time CAT 100%iler

Start your IIM journey with the right preparation and crack CAT 2026.