Изображение упражнения

Amanita, let's break down the problem step by step and solve it together!

Step-by-Step Plan

  1. Understand the Problem:
    We are given a differential equation:

x3y+x2y2xy+2y=2x4 x^3 y''' + x^2 y'' - 2x y' + 2y = 2x^4

and told that x,x2,x, x^2, and 1/x1/x are solutions to the homogeneous version (where the right side is 0).

  1. Write the Homogeneous Equation:
    The homogeneous equation is:

x3y+x2y2xy+2y=0 x^3 y''' + x^2 y'' - 2x y' + 2y = 0

  1. Find a Particular Solution:
    Since the right side is 2x42x^4, we need to find a particular solution to the non-homogeneous equation.
    We will use the method of undetermined coefficients or variation of parameters. Since the right side is a polynomial, let's try a particular solution of the form yp=Ax4y_p = A x^4.

  2. Substitute ypy_p into the Equation:
    We will compute the derivatives of ypy_p, substitute them into the original equation, and solve for AA.

  3. Write the General Solution:
    The general solution will be the sum of the homogeneous solution and the particular solution.


Step 1: Assume a Particular Solution

Let’s try yp=Ax4y_p = A x^4.

Calculate the derivatives:

  • yp=4Ax3y_p' = 4A x^3
  • yp=12Ax2y_p'' = 12A x^2
  • yp=24Axy_p''' = 24A x

Step 2: Substitute into the Differential Equation

Plug these into the original equation:

x3(24Ax)+x2(12Ax2)2x(4Ax3)+2(Ax4)=2x4x^3 (24A x) + x^2 (12A x^2) - 2x (4A x^3) + 2(A x^4) = 2x^4

Let's simplify each term:

  • x324Ax=24Ax4x^3 \cdot 24A x = 24A x^4
  • x212Ax2=12Ax4x^2 \cdot 12A x^2 = 12A x^4
  • 2x4Ax3=8Ax4-2x \cdot 4A x^3 = -8A x^4
  • 2Ax42A x^4

Add them up:

24Ax4+12Ax48Ax4+2Ax4=2x424A x^4 + 12A x^4 - 8A x^4 + 2A x^4 = 2x^4

Combine like terms:

(24A+12A8A+2A)x4=2x4(24A + 12A - 8A + 2A) x^4 = 2x^4

30Ax4=2x430A x^4 = 2x^4

Step 3: Solve for AA

Set the coefficients equal:

30A=230A = 2

A=230=115A = \frac{2}{30} = \frac{1}{15}


Step 4: Write the Particular Solution

So, the particular solution is:

yp=115x4y_p = \frac{1}{15} x^4

Step 5: General Solution

The general solution is:

y(x)=C1x+C2x2+C31x+115x4y(x) = C_1 x + C_2 x^2 + C_3 \frac{1}{x} + \frac{1}{15} x^4


Final Answer for a Particular Solution:

yp=115x4\boxed{y_p = \frac{1}{15} x^4}

Amanita, the particular solution to the given equation is 115x4\frac{1}{15} x^4.