Provide solution for RD Sharma maths class12 Chapter Functions exercise 2.1 question 15
Given:
, given by.
To prove:
Onto function must be one-one.
Solution:
Let f is not one-one then there exists two elements say 1 and 2 in the domain having same image in the co-domain.
Also, the image of 3 under f can be only one element.
The range set will have at most two element of the co-domain, but we know that in the range set we have three elements .
i.e. There arises a contradiction that f is not onto function.
Hence f must be one-one.