© examsnet.com
Question : 22
Total: 29
Find the particular solution of the following differential equation:
(x + 1)
= 2 e − y - 1 ; y = 0 when x = 0
(x + 1)
Solution:
(x + 1)
= 2 e − y - 1
⇒
=
⇒
=
Integrating both sides, we get:
∫
= log |x + 1| + log C ... (1)
Let 2 -e y = t
∴
( 2 − e y ) = {dt}/{dy}$$
⇒ -e y =
⇒e y dy = - dt
Substituting this value in equation 1 , we get:
∫ -
= log |x + 1| + log C
⇒ - log |t| = log |C (x + 1)|
⇒ - log |2 -e y | = log |C (x + 1)|
⇒
= C (x + 1)
⇒ 2 -e y =
... (2)
Now, at x = 0 and y = 0, equation 2 becomes:
⇒ 2 - 1 =
⇒ C = 1
Substituting C = 1 in equation 2 , we get:
2 -e y =
⇒e y = 2 -
⇒e y =
⇒e y =
⇒ y = log|
| , (x ≠ - 1)
This is the required particular solution of the given differential equation.
⇒
⇒
Integrating both sides, we get:
∫
Let 2 -
∴
⇒ -
⇒
Substituting this value in equation 1 , we get:
∫ -
⇒ - log |t| = log |C (x + 1)|
⇒ - log |2 -
⇒
⇒ 2 -
Now, at x = 0 and y = 0, equation 2 becomes:
⇒ 2 - 1 =
⇒ C = 1
Substituting C = 1 in equation 2 , we get:
2 -
⇒
⇒
⇒
⇒ y = log
This is the required particular solution of the given differential equation.
© examsnet.com
Go to Question: