Page 11 - E booklet prep 3 bader 2025 b_Neat

3-Functions

A relation from X to Y is said to be a function if:

Each element of X appears only once as a first projection in one of the
ordered pairs of the relation

Written as:

f : X ? Y and read as f is a function from X to Y

Notes :

1) If ( x , y ) ? to the function then y is called the image of x by the
function f

In the two forms

f:X ? Y or f (x) = y

2) If f : X ? Y then:
? X is called ( the domain )
? Y is called ( the codomain )
? The set of images of the element of X is called ( the range )
where: range ? the codomain

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