newbie | finding roots of polynomial



  After 15+ years of using Maple, I've decided to take latest build of 
Maxima for a spin (motivated to some degree by the desire to find a 
symbolic algebra program I can have my students use at no cost). I've 
done a a bit of 'fooling' with Maxima (learn by doing), and am stuck on 
something which seems pretty trivial.

Consider f : -x^3+x+0.25=0

Now, I know from Maple that the roots of this polynomial are -0.83757, 
-0.26959, and 1.1072. However, in Maxima, if I try

solve(f,x);

I get something is is bizarrely large and convoluted -- all sorts of 
fractions, and square roots, and the like. I tried toggling different 
levels of float, but I still don't end up with a nice simple solution 
vector containing these three solutions.

Pointers to the obvious solution? Thanks in advance (remember, newbie, 
more or less, so set phasers to 'singe only'). ;-)  I'll leave my 
implicit differentiation question to a followup post. ;-)