Please solve RD Sharma class 12 Chapter Functions exercise 2.1 question 20 maths textbook solution.
Let  and 
 are two function defined by 
 and 
.
Clearly  and 
 are one-one functions.
Now,     given by
Let       
    defined by 
Now,    
since, the two elements have the same image.
 is not one-one.
Hence,      is not one-one.