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Question : 22
Total: 29
Find the general solution of the differential equation,
x log x
+ y =
log x
OR
Find the particular solution of the differential equation satisfying the given conditions:
= y tan x , given that y = 1 when x = 0.
x log x
OR
Find the particular solution of the differential equation satisfying the given conditions:
Solution:
x log x
+ y =
log x
Dividing all the terms of the equation by xlogx, we get
⇒
+
=
This equation is in the form of a linear differential equation
+ Py = Q , where { =
and Q =
Now, I.F. =e ∫ P d x = e ∫
d x = e l o g ( l o g x ) = log x
The general solution of the given differential equation is given by
y × I.F. = ∫ (Q × I.F.) dx + C
⇒ y log x = ∫(
l o g x ) dx
⇒ y log x = 2 ∫( l o g x ×
) dx
= 2 [log x × ∫
dx - ∫ {
( log x ) × ∫
d x } dx]
= 2[ log x ( −
) − ∫ (
× ( −
) ) d x ]
= 2[ −
+ ∫
d x ]
= 2[ −
−
] + C
So the required general solution is y log x =−
(1 + log x) + C
OR
= y tan x
⇒
= tan x dx
On integration, we get
∫
= ∫ tan x dx
⇒ log y = log (sec x) + log C ... (1)
⇒ log y = log (C sec x)
⇒ y = C sec x
Now,it is given that y = 1 when x = 0
⇒ 1 = C × sec 0
⇒ 1 = C × 1
∴ C = 1
Substituting C = 1 in equation (1), we get
y = sec x as the required particular solution.
Dividing all the terms of the equation by xlogx, we get
⇒
This equation is in the form of a linear differential equation
Now, I.F. =
The general solution of the given differential equation is given by
y × I.F. = ∫ (Q × I.F.) dx + C
⇒ y log x = ∫
⇒ y log x = 2 ∫
= 2 [log x × ∫
= 2
= 2
= 2
So the required general solution is y log x =
OR
⇒
On integration, we get
∫
⇒ log y = log (sec x) + log C ... (1)
⇒ log y = log (C sec x)
⇒ y = C sec x
Now,it is given that y = 1 when x = 0
⇒ 1 = C × sec 0
⇒ 1 = C × 1
∴ C = 1
Substituting C = 1 in equation (1), we get
y = sec x as the required particular solution.
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