Explanation
1. Rearrange the Equation
Rewrite the equation to isolate dydx:
Now, move the term containing x to the left side:
2. Identify the Linear Form
This is a first-order linear differential equation of the form dydx+P(y)x=Q(y), where:
-
P(y)=1+y21
-
Q(y)=1+y2tan−1y
3. Find the Integrating Factor (I.F.)
4. General Solution Formula
The general solution is given by:
x⋅(I.F.)=∫Q(y)⋅(I.F.)dy+C
x⋅etan−1y=∫(1+y2tan−1y)⋅etan−1ydy+C
5. Evaluate the Integral
To solve ∫1+y2tan−1yetan−1ydy, use substitution:
Let t=tan−1y, then dt=1+y21dy.
The integral becomes:
Using integration by parts (∫udv=uv−∫vdu):
-
u=t⟹du=dt
-
dv=etdt⟹v=et
∫tetdt=tet−∫etdt=tet−et=(t−1)et
Substitute back t=tan−1y:
∫1+y2tan−1yetan−1ydy=(tan−1y−1)etan−1y
6. Final General Solution
Substitute the integral back into the solution equation:
xetan−1y=(tan−1y−1)etan−1y+C
Divide the entire equation by etan−1y (or multiply by e−tan−1y):
Result:
The general solution is: