contestada

Statement 5.109. Letf:X→Ybe a function. Then the functionfis a bijection iff the relation{(y,x)∈Y×X∣(x,y)∈f}is a function.

Respuesta :

Let f:X→Ybe a function. Then the function  f  is a bijection if the relation   {(y ,x)∈Y×X∣ (x ,y)∈f}  is a function.  

Assume that X→Y is a bijective function.  

i.e. f:X→Y is one-one and onto function.

so different elements in X have different images in Y

and b ∈ Y there exists a ∈ X such that f(a)=b.

R= {(y ,x)∈Y×X∣(x ,y)∈f}  is a relation

we wish to prove R is a function.

R is a relation from Y to X  

let  Y∈Y by assumption f is bijection function from X to Y

for all y ∈ Y there exists X∈ X   such that f(x)=y.

so for every element in Y there is mapping element in X.
if (x ,y) ∈  f then (y ,x) ∈ R

therefore R is a function.        

   

let X1, X2, ∈ X then there exists some y1, y2,∈ y such that

take f ( x1 )= y1 and f( x2)=y2

by assumption R is a function from Y to X that is inverse of f is existing means f is bijection.

for bijective functions only inverse exists.



If f:X→Y is a function. Then the function f is a bijection if the relation

{(y ,x)∈Y×X∣(x, y)∈f}  is a function.

To learn About  bijection:        
 https://brainly.com/question/14871175  
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