f : A→B and f(x) = x^2
Here 1, 4, 7 and 8 are pre-images and 1, 16 49, 64 are images
Verbal explanation assisted by two sets prepared in Braille may help the child to
understand the ideas of image and pre-image.
- Domain and Co-domain
Let f : A→B be a function. Then A is called the domain and B is called the co-domain
of the function f.
The idea may be taught orally with necessary text material in Braille.
Eg. :
f : A→B and f(x) = x-1
Here, domain = {2, 4, 6}
Co-domain = {1, 3, 5, 7}
- Range
The set of elements in the co-domain, (which are images) form a subset of the
co-domain and is called the range of ‘f’.
Eg. : In the above example, range = {1, 3, 5}
Note:
- If an element of the domain has more than one image in the co-domain then it is
not a function.
- More than one element of the domain may be mapped to the same element in the
co-domain.
2
4
6
1
3
5
7
A B
