Function

Rarely Tested

Function

## Definition / Concept

A function $f$ from $A$ to $B$ assigns exactly one element of $B$ to every element of $A$.

## Formula

$$f:A\to B$$

$$\forall x\in A,\ \exists!\,y\in B\text{ such that }y=f(x)$$

## Terminologies

- Domain → Set of permissible input values.

- Codomain → Set in which the output values are specified.

- Range → Set of actual output values.

- Image → Output corresponding to a particular input.

- Pre-image → Input corresponding to a particular output.

## Conditions / Special Cases

Every element of the domain must have exactly one image.

Different elements of the domain may have the same image.

## Usage

- Forms the basis of algebraic, graphical and calculus-based function problems.

Question 1

The number of the real solutions of the equation:
$$x|x+3|+|x-1|-2=0$$ is

Question 2

Let $$f(x)=\dfrac{2^{x+2}+16}{2^{2x+1}+2^{x+4}+32}$$. Then the value of $$8\left(f\!\left(\dfrac{1}{15}\right)+f\!\left(\dfrac{2}{15}\right)+\cdots+f\!\left(\dfrac{59}{15}\right)\right)$$ is equal to:

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