(d2-3d+2)y=sin3x

4 min read Jul 03, 2024
(d2-3d+2)y=sin3x

Solving the Equation (d2-3d+2)y=sin3x

In this article, we will explore the solution to the differential equation (d2-3d+2)y=sin3x. This is a second-order linear ordinary differential equation (ODE) with a sinusoidal forcing function.

Background

Before we dive into the solution, let's review some background concepts:

  • Differential Equations: A differential equation is a mathematical equation that involves an unknown function and its derivatives.
  • Linear ODEs: A linear ODE is a type of differential equation where the derivatives of the unknown function are proportional to the function itself.

Solution Method

To solve the differential equation (d2-3d+2)y=sin3x, we will use the method of undetermined coefficients. This method involves assuming a particular solution of the form:

y_p = A sin3x + B cos3x

where A and B are constants to be determined.

Finding the Particular Solution

To find the particular solution, we will substitute y_p into the original differential equation:

(d2-3d+2)(A sin3x + B cos3x) = sin3x

Expanding the left-hand side and collecting terms, we get:

(-9A + 3B) sin3x + (3A + 9B) cos3x = sin3x

Equating coefficients, we have:

-9A + 3B = 1 ... (1) 3A + 9B = 0 ... (2)

Solving the system of equations (1) and (2), we get:

A = -1/10 and B = 1/30

Therefore, the particular solution is:

y_p = (-1/10) sin3x + (1/30) cos3x

Finding the General Solution

To find the general solution, we need to find the complementary function y_c. The complementary function is a solution to the homogeneous equation:

(d2-3d+2)y = 0

The characteristic equation is:

r^2 - 3r + 2 = 0

Solving the characteristic equation, we get:

r = 1 and r = 2

Therefore, the complementary function is:

y_c = C1 e^x + C2 e^(2x)

where C1 and C2 are arbitrary constants.

General Solution

The general solution to the differential equation (d2-3d+2)y=sin3x is:

y = y_p + y_c

y = (-1/10) sin3x + (1/30) cos3x + C1 e^x + C2 e^(2x)

where C1 and C2 are arbitrary constants.

Conclusion

In this article, we have solved the differential equation (d2-3d+2)y=sin3x using the method of undetermined coefficients. The general solution involves a particular solution and a complementary function. The particular solution is a sinusoidal function that satisfies the original differential equation, while the complementary function is a solution to the homogeneous equation.

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