मराठी

Linear Differential Equations

Advertisements

Topics

  • Beta and Gamma Functions, Differentiation Under Integral Sign and Exact Differential Equation old
  • Beta and Gamma Functions and Its Properties
  • Rectification of Plane Curves
  • Differential Equation of First Order and First Degree
  • Differential Calculus old
  • Linear Differential Eqaution with Constant Coeffiecient
  • Linear Differential Equations(Review), Equation Reduciable to Linear Form, Bernoulli’S Equation
  • Cauchy’S Homogeneous Linear Differential Equation and Legendre’S Differential Equation, Method of Variation of Parameters
  • Simple Application of Differential Equation of First Order and Second Order to Electrical and Mechanical Engineering Problem
  • Numerical Solution of Ordinary Differential Equations of First Order and First Degree and Multiple Integrals old
  • Multiple Integrals‐Double Integration
  • Taylor’S Series Method,Euler’S Method,Modified Euler Method,Runga‐Kutta Fourth Order Formula
  • Multiple Integrals with Application and Numerical Integration old
  • Triple Integration
  • Application to Double Integrals to Compute Area, Mass, Volume. Application of Triple Integral to Compute Volume
  • Numerical Integration
  • Differential Equations of First Order and First Degree
  • Linear Differential Equations with Constant Coefficients and Variable Coefficients of Higher Order
    • Linear Differential Equation with Constant Coefficient‐ Complementary Function
    • Particular Integrals of Differential Equation
    • Cauchy’S Homogeneous Linear Differential Equation
    • Legendre’S Differential Equation
    • Method of Variation of Parameters
  • Numerical Solution of Ordinary Differential Equations of First Order and First Degree, Beta and Gamma Function
    • Taylor’S Series Method
    • Euler’S Method
    • Modified Euler Method
    • Runga‐Kutta Fourth Order Formula
    • Beta and Gamma Functions and Its Properties
  • Differentiation Under Integral Sign, Numerical Integration and Rectification
    • Differentiation Under Integral Sign with Constant Limits of Integration
    • Numerical Integration‐ by Trapezoidal
    • Numerical Integration‐ by Simpson’S 1/3rd
    • Numerical Integration‐ by Simpson’S 3/8th Rule
    • Rectification of Plane Curves
  • Double Integration
    • Double Integration‐Definition
    • Evaluation of Double Integrals
    • Change the Order of Integration
    • Evaluation of Double Integrals by Changing the Order of Integration and Changing to Polar Form
  • Triple Integration and Applications of Multiple Integrals
    • Triple Integration Definition and Evaluation
    • Application of Double Integrals to Compute Area
    • Application of Double Integrals to Compute Mass
    • Application of Double Integrals to Compute Volume
    • Application of Triple Integral to Compute Volume

Notes

A differential equation of the from `(dy)/(dx) + Py = Q`
To solve the first order linear differential equation of the type
`(dy)/(dx) + Py= Q`    ...(1)
Multiply both sides of the equation by a function of x say g (x) to get
g(x)`(dy)/(dx) + P.(g(x)) y = Q . g(x)`   ...(2)
Choose g(x) in such a way that R.H.S. becomes a derivative of y . g (x).

i.e. `g(x)(dy)/(dx) + P.g(x)y = d/(dx) [y.g(x)]`

or `g(x) (dy)/(dx) + P.g(x)y ` = g(x)`(dy)/(dx) + y g'(x)`

`=> P.g(x) = g'(x)`
o r P = g'(x)/g(x)

Integrating both sides with respect to x, we get 

`int Pdx = int (g'(x))/g(x)dx`

or `int P.dx = log (g(x))`

or g(x) = `e^(int Pdx)`

On multiplying the equation (1) by g(x) =`e^( int Pdx)` , the L.H.S. becomes the derivative of some function of x and y. This function
g(x) = `e^(int P dx)` is called Interrating Factor (I.F.) of the  given differential equation. 

Substituting the value of g (x) in equation (2), we get

`e^(Pdx) (dy)/(dx) + Pe^(int Pdx) y = Q . e^(Pdx)`

Or `d/(dx) (ye^(intPdx)) = Qe^(int Pdx)`

Integrating both sides with respect to x, we get

`y.e^(int P dx) = int (Q.e^(int P dx)) dx`  Or 
`y = e^(-int Pdx) = int (Q.e^(int P dx)) dx + C`
which is the general solution of the differential equation.

Steps involved to solve first order linear differential equation:

(i) Write the given differential equation in the form `(dy)/(dx)` + Py = Q  where P, Q are constants or functions of x only.

(ii) Find the Integrating Factor (I.F) = `e^(int Pdx)`

(iii) Write the solution of the given differential equation as
y (I.F) = `int`(Q × I.F )dx + C
In case, the first order linear differential equation is in the form `(dx)/(dy) + P_1x = Q_1`, where, `P_1` and `Q_1` are constants or functions of y only. 
Then I.F = `e^(P_idy)` and the solution of the differential equation is given by 
 x . (I.F) = `int (Q_1 xx I.F)` dy + C

Shaalaa.com | Differential Equation part 17 (1st order linear differential Equation)

Shaalaa.com


Next video


Shaalaa.com


Differential Equation part 17 (1st order linear differential Equation) [00:11:43]
S

Related QuestionsVIEW ALL [1]

Advertisements
Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Course
Use app×