The differential equation is
.
(a)
\Find the solution of the differential equation.
\


Apply integral on each side.
\
Apply power rule of integral :
.



\ \

.
.
At the initial time
and
.


.
Susbtitute
in
.



Therefore, the solution of the equation is
.
(b) Find the value of
when
. \ \







As
tends to left side of
then the condition is
.
When there is a small positive number to a negative exponent, then the value is very positive number.
\Hence,
the expression approaches to
.
Therefore,
.
(c)
\The equation is
.
The doomd day will happen at
.
The number of rabits breed initially is
.
The numbers of rabits breed after three months are
.
The prolific breed of rabbits has the growth term is
.
The function is
, where the growth term is
.
Compare equations
and
.

The value of
.Susbtitute
,
,
and
in
.

Substitute
,
,
in
.

The doomsday will happen after
.
(a) The solution of the equation is
.
(b)
at
.
(c) The droomday will happen after
.