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Rationality certification (Posted on 2016-10-27) Difficulty: 3 of 5
Given a and b are two rational numbers, fulfilling the equality
a^3 + 4a^2*b = 4a^ 2 + b^4.

Prove that the value of sqrt(a-1) is a rational number.

No Solution Yet Submitted by Ady TZIDON    
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Hints/Tips errata - Comment 2 of 2 |

att:solvers


...Prove that the value of sqrt(a-1) is a rational number

was   sqrt(a)-1 in the original text, not sqrt(a-1)

Clearly if   sqrt(a)-1=m/n 

  then  sqrt(a)=1+m/n= (m+n)/n   ,   a rational number

Brian has actually discovered the error and solved  assuming 
"Prove that the value of sqrt(a) is a rational number" 


  Posted by Ady TZIDON on 2016-11-10 04:10:50
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