Substituting the value of C in equation (3), we get the equation of the required curve as
3
2
5
y3
=x
+
   or   
1
2
3
(3
15)
y
x
=
+
Example 14 In a bank, principal increases continuously at the rate of 5% per year In
how many years Rs 1000 double itself Solution Let P be the principal at any time t According to the given problem,
dp
dt  =
5
P
⎛100
⎞×
⎜
⎟
⎝
⎠
or
dp
dt  = P
20