logo

Ask Questions, Get Answers

 
X
 Search
Want to ask us a question? Click here
Browse Questions
Ad
Home  >>  CBSE XII  >>  Math  >>  Differential Equations
0 votes

Solve the differential equation$y\;e^{\large\frac{x}{y}}\;dx=\bigg(x\;e^{\Large\frac{x}{y}}+y^2\bigg)dy\;(y\neq0)$

Can you answer this question?
 
 

1 Answer

0 votes
Toolbox:
  • If the linear differential equation is of the form $\large\frac{dx}{dy}$$ = F(x,y)$, is said to be homogenous if F(x,y) is a homogenous function of degree 0.
  • This type of equation can be solved by substituting x= vy and $\large\frac{dx}{dy} =$$ v+y\large\frac{dv}{dy}$
Step 1:
Given :$y\;e^{\large\frac{x}{y}}\;dx=\bigg(x\;e^\frac{x}{y}+y^2\bigg)dy$
we can write the equation as $\large\frac{dx}{dy} = \frac{[xe^{\Large(x/y)} +y^2]}{y.e^{\Large(x/y)} }$
Using the information in the tool box, we understand this given equation is a homogenous function of dergree 0,
Step 2:
let us substitute $x= vy$ and $\large\frac{dx}{dy} $$= v + y\large\frac{dv}{dy}$
$v + y\large\frac{dv}{dy} =\large\frac{ [vy.e^v + y^2]}{y.e^v}$
taking y as the common factor and cancelling we get,
$v + y\large\frac{dv}{dx} =\frac{ [ve^y + y]}{e^v}$
bringing v from LHS to RHS we get
$y\large\frac{dv}{dy} =\frac{ y}{e^v }$
seperating the variables we get,
$e^vdv = dy$
Step 3:
Integrating on both sides we get,
$\int e^vdv=\int dy$
$e^v=y+C$
Substituting for $v=\large\frac{ x}{y}$ we get,
$e^{\Large\frac{x}{y}}=y+C$
This is the required solution.
answered Jul 30, 2013 by sreemathi.v
 

Related questions

Ask Question
student study plans
x
JEE MAIN, CBSE, NEET Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App
...