In[]:=
DSolve[D[B[t],t]==rB[t]–P,B[t],t]
Out[]=
B[t]+
P
r
rt
1
In[]:=
DSolve[{D[B[t],t]==rB[t]–P,B[0]==B0},B[t],t]//FullSimplify
Out[]=
B[t]
P+(–P+B0r)
rt
r
In[]:=
eqn=D[P[t],t]rP[t]–M
Out[]=
′
P
In[]:=
soln=DSolve[{eqn},P[t],t,DiscreteVariables{t}]
Out[]=
P[t]+
M
r
rt
1
In[]:=
soln=DSolve[{eqn/.M0,P[0]P0},P[t],t]
Out[]=
{{P[t]P0}}
rt
In[]:=
First@First@soln/.t1//N
Out[]=
P[1.]59.343
sol=NDSolve[{y'[t]a[t],WhenEvent[Mod[t,1],a[t]y[t]],y[0]1,a[0]1},{y,a},{t,0,4},DiscreteVariables{a}]
Out[]=
yInterpolatingFunction
,aInterpolatingFunction
 |  |
|
|  |
|
In[]:=
Plot[Evaluate[{y[t],a[t]}/.sol],{t,0,4}]
Out[]=
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