Q.

Let a function f:(0,)[0,) be defined by f(x)=|11x|. Then, f is 

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a

Both injective as well as surjective 

b

Injective only

c

Not injective but it is surjective

d

Neither injective nor surjective 

answer is C.

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Detailed Solution

We have,   f(x)=|x1|x={(x1)x,      if0<x1     x1x,        if  x>1

={1x1,      if0<x1    11x,        if  x>1

Now, let us draw the graph of   y=f(x)
 Note that when x0, then f(x), when x=1, then f(x)=0, and when x, then  f(x)1
Question Image

 

 

 

 

 

 

Clearly,  f(x) is not injective because if f(x)<1, then f is many one, as shown in figure.
          Also, f(x) is not surjective because range of f(x) is [0,]  and but in problem co-domain is (0,), which is wrong.  

f(x) is neither injective nor surjective 

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