# Length of curve integral

1. Jan 1, 2014

### applestrudle

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

2. Jan 1, 2014

### LCKurtz

Is that last term supposed to be $\frac {a^2}{12x}$ or $\frac{a^2x}{12}$?
Did you leave out the $1$? It would help if you showed your work.

3. Jan 1, 2014

### applestrudle

the last term is a^2 / (12x) x in the denominator.

yeah i left out the 1, that was a typo.

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

thanks

4. Jan 1, 2014

### LCKurtz

Re-check your arithmetic for that first term and you should be able to work out that the quantity under the radical is a perfect square.