TI 89 titanium calc problems

[LinusX]

Hey guys, so I've been using a TI-89 calc this year with no serious problems until
I did the Neap 2007 exam 2 paper, question 1 part d. I equated the volume
equation to 15 and solved for a, but my calc doesn;t give me an answer, just
a massive string of logs. When I looked at the solutions, they had a screen dump of the 89
and they worked it out using exactly what i put in.

Any ideas? Anyone actually using a TI 89 titanium?

[plato]

What settings do you have? Auto or exact? Try changing this.
I don't have the question so I cannot be more precise.

[LinusX]

i tried all the settings, approx, exact and auto. I just cannot get it to work.

The equation is Volume = pi * integral ( 16/ (x^3 +4) , x , 0 , a)
Volume is 15, hence I let the equaltion = 15 in solver.
When I solve for a, I just get this quadratic within a log and  no matter what I do
I never get the solution for a.

What could be the problem?

[plato]

I typed in  pi * integral ( 16/ (x^3 +4) , x , 0 , a) =15
and got an answer of 1.34959966284474

This is not an exact answer but at least it is numerical. Is the actual answer given as being in terms of pi??
Did you have this complete line including the =15 part?

By the way, I also tried just using Solve( pi * integral ( 16/ (x^3 +4) , x , 0 , a) =15,a) and got a domain error after about 30 seconds.