maths.free › Differential Equations › Nonhomogeneous equations

Nonhomogeneous equations

Driving forces: homogeneous solution plus a particular solution.

With a forcing term on the right, the general solution is the homogeneous solution plus any one particular solution. Undetermined coefficients guesses the particular solution in the shape of the forcing (exponential, polynomial, sinusoid); variation of parameters handles the rest.

Megdolgozott példa · y'' - 3y' + 2y = e^x

Differential-Equations · Differential-Equations

Y'' - 3y' + 2y = e^x

2 y{\left(x \right)} - 3 \frac{d}{d x} y{\left(x \right)} + \frac{d^{2}}{d x^{2}} y{\left(x \right)} = e^{x}

Lépésről lépésre

  1. 2 y{\left(x \right)} - 3 \frac{d}{d x} y{\left(x \right)} + \frac{d^{2}}{d x^{2}} y{\left(x \right)} = e^{x}

    The differential equation.

  2. \text{order } 2

    Order 2: the highest derivative present.

  3. \text{Undetermined coefficients}

    Solve the homogeneous part from the characteristic equation, then guess a particular solution shaped like the right-hand side.

  4. r^{2} - 3 r + 2 = 0

    Characteristic equation of the homogeneous part (substitute y = e^{rx}).

  5. r = 2,\ r = 1

    Its roots.

  6. y{\left(x \right)} = \left(C_{1} + C_{2} e^{x} - x\right) e^{x}

    General solution (C₁, C₂ … are arbitrary constants).

  7. \checkmark

    Verified: substituting the solution back into the equation gives 0.

Mutasd meg a választ!
y{\left(x \right)} = \left(C_{1} + C_{2} e^{x} - x\right) e^{x}

Most te. Válasszon egy problémát, vagy gépelje vagy rajzolja le a saját. Minden lépés, a kép, a válasz elrejtve, amíg nem kérdezi.

Dolgozz tovább!

Egy ingyenes fiók jegyzeteket ad minden leckéről, egy feljegyzést arról, hogy mit végeztél el, a megoldott problémáidról egy helyen, és egy oktatót, akit megkérdezhetsz erről az oldalról. A matematika maga mindenki számára nyitva áll, bejelentkezve vagy sem.

Regisztrálj! Bejelentkezés

Itt használt szimbólumok

Koppintson a teljes definícióra, a képre és arra, hogy mit jelent minden betű.

Hogyan kell: Nonhomogeneous equations

  1. The differential equation.
  2. Order 2: the highest derivative present.
  3. Solve the homogeneous part from the characteristic equation, then guess a particular solution shaped like the right-hand side.
  4. Characteristic equation of the homogeneous part (substitute y = e^{rx}).
  5. Its roots.
  6. General solution (C₁, C₂ … are arbitrary constants).
  7. Verified: substituting the solution back into the equation gives 0.

Kérdések, amiket az emberek feltesznek

What is a differential equation?

An equation whose unknown is a function, relating it to its own derivatives. "The rate of growth is proportional to the population" is y′ = ky, and solving it means finding y as a function of time.

Why does the solution have arbitrary constants?

Integrating loses information: many functions share the same derivative. An n-th order equation has n constants, fixed by n initial or boundary conditions.

Még több Differential Equations

Separable equationsFirst-order linear equationsSecond-order, constant coefficientsModelling with differential equations