@Rouben Rostamian  

Thank you very much, just what I was needing.

@Carl Love 

Thank you. 

It is the proper form of the second command that is escaping me, the solution of the returned integral.  After posting, I realized that generalizing the constants was likely misleading, so, here the exact (messy) form of my first command -

sol := dsolve({diff(f(t), t) = (.21*.2894606222-.21*(1.158611162/((1+0.4836862955e-1*t)*(1/(1+0.4836862955e-1*t))^.1986136226))-.2894606222*f(t))/V, f(0) = .21})

Wish to get the second command right to return f(t).