Find the general solution of the given differential equation. x (dy/dx) + 3y = x3 - x
Solution:
Given,
Differential equation x (dy/dx) + 3y = x3 - x
Dividing both sides by x,
dy/dx + 3y/x = x2 - 1 --- (1)
Rewriting the given equation in first order differential form
(dy/dx) + Py = Q
Where, P = 3/x
Q = x2 - 1
Now, integrating factor,
I.F. = e∫p dx
I.F. = e∫(6/x) dx
= x6
On multiplying equation (1) by I.F., we get,
I.F × y = ∫Q × I.F. dx
x6 × y = ∫(x2 - 1)x6. dx
d(x6y) = ∫(x8 - x6).dx
d(x6y) = (x8 - x6) dx
∫d(x6y) = ∫(x8 - x6) dx
x6y = (1/9)x9 - (1/7)x7 + C
Dividing both sides by x6,
y = (1/9)x3 - (1/7)x + c/x6
Therefore, the general solution is y = (1/9)x3 - (1/7)x + c/x6.
Find the general solution of the given differential equation. x (dy/dx) + 3y = x3 - x
Summary:
The general solution of the given differential equation x (dy/dx) + 3y = x3 - x is y = (1/9)x3 - (1/7)x + c/x6.
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