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1)

The function f:R[12,12] defined as  f(x)=x1+x2is


A) invertible

B) injective but not surjective

C) surjective but not injective

D) neither injective nor surjective

Answer:

Option C

Explanation:

We have f(x)=x1+x2

   f(1x)=1x1+1x2=x1+x2=f(x)

  f(12)=f(2) or f(13)=f(3)   and so on 

  So, f(x) is many -one function 

   Again , let y=f(x)

    y=x1+x2

     y+x2y=x

  yx2x+y=0

As,    $x\epsilon  R

   (1)24(y)(y)0

   14y20

   yϵ[12,12]

Range= Codomain= [12,12]

    So, f(x) is surjective.

   Hence , f(x) is surjective but not injective.