READING:     II     1     F7                    Back to reading:     II     1     F6
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CHAPTER II [:] The Real Number System [...] 1. THE FIELD PROPERTIES. "end quote
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F7:       (a)= a

For any real number   a,    (a)= a
  1  
  =  
  (a) · a  
  existence of multiplicative inverse  
  But  
   
   
  we also have  
  1  
  =  
  a · a  
  existence of multiplicative inverse  
  And  
   
   
  both of the above equations are of the form  
  1  
  =  
  x · a  
  And therefore we have the desired result by F4.  

on to F8