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.
...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"