Length of curve integral

1. The problem statement, all variables and given/known data



Find the length of the curve y = x^3/a^2 + a^2/12x



between a and a/2





2. Relevant equations



Length L = integrate (1+ dy/dx)^2)^0.5



3. The attempt at a solution



I got to



integrate (9x^4/a^2 + 1/2 + a^4/144x^4)^0.5



but I can't simplify it