A Formula or an equation can be used
Let a = { 1, 2, 3 } and B = { 5, 7, 8 }
Note that f ( 1 ) = 2 ( 1 ) + 3 = 5
f ( 2 ) = 2 ( 2 ) + 3 = 7 and
f ( 3 ) = 2 ( 3 ) + 3 = 9
i.e. f ( x ) = 2 x + 3 where x Î A and f ( x ) Î B.
This is the formula which exhibits the function 'f'
Graphs can be used.
Click here to enlarge
Note that a vertical line parallel to yaxis, intersects the graph at one and only one point.
A table may be used. Consider y = 2x + 3 then,
Types of Functions
 One  One ( 1  1 ) Function
A function f : A ® B is oneone if different elements of A have different images in B. It is also called 'injection'.
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Index
6.1 Relations
6.2 Functions 6.3 Variation
Chapter 7
