[R] generate random number

[Ragnhild Sørum]

Hi

I would like to generate some(ss) random numbers from a density distribution 
f(x).
In my case f(x) = a*exp(b*x),  ex. a=2, b=0.5,   and x is only defined 
between x1 and x2,  ex.  from -6 to -2.5.

Any suggestions? Can I use rexp?

Thanks,
Ragnhild