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Multiple Choice
Solve the differential equation using the method of undetermined coefficients. What is the general solution?
A
B
C
D
Verified step by step guidance
1
Step 1: Identify the type of differential equation. The given equation is a second-order linear differential equation with constant coefficients: 4y'' + y' + y = x^2 - 5x. The right-hand side (x^2 - 5x) suggests that the method of undetermined coefficients is appropriate for solving this equation.
Step 2: Solve the homogeneous equation. First, consider the associated homogeneous equation: 4y'' + y' + y = 0. Solve this by finding the characteristic equation, which is obtained by substituting y = e^(rx): 4r^2 + r + 1 = 0. Solve this quadratic equation for r to find the roots, which will determine the complementary solution.
Step 3: Determine the particular solution. For the non-homogeneous part (x^2 - 5x), propose a trial solution based on the form of the right-hand side. Since the right-hand side is a polynomial of degree 2, the trial solution should be of the form y_p = Ax^2 + Bx + C. Substitute y_p into the original equation to solve for the coefficients A, B, and C.
Step 4: Combine the solutions. The general solution to the differential equation is the sum of the complementary solution (from Step 2) and the particular solution (from Step 3). Write the general solution as y = y_c + y_p, where y_c is the solution to the homogeneous equation and y_p is the particular solution.
Step 5: Verify the solution. Substitute the general solution back into the original differential equation to ensure that it satisfies the equation. This step confirms the correctness of the solution and ensures that all terms are accounted for.