r:=0.5
K:=10
p0:=0.5
a:=-1
rez:=Evaluate[p[t]/.DSolve[{p'[t]==r*p[t]*(1-p[t]/K-a),p[0]==p0},p[t],t]]
rez
Plot[{rez,K},{t,0,20},AxesLabel->{t,Populacija},AxesOrigin->{0,0},PlotRange->{{0,20}, {0,20}}]
{((10 (E^(r t)) x0)/(10-x0+(E^(r t)) x0))}



Show[GraphicsArray[Partition[Table[
Plot[Evaluate[Table[(( 10*(E^(r t))* x0)/(10-x0+((E^(r t)))*x0)),{x0,0,1,.05}]],{t,0,10},
DisplayFunction->Identity,
PlotLabel->TraditionalForm[HoldForm[r]==PaddedForm[r,{2,1}]],
AxesLabel->TraditionalForm/@{t,x[t]},PlotStyle->Hue/@Range[0,1,.05],PlotRange->All],
{r,-1,1.5,.5}],3]
],ImageSize->500]