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Find a particular solution to the differential equation using the Method of Undetermined Coefficients.

(d2y/dx2)-5(dy/dx)+8y = xex

User Xdg
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The characteristic equation of the homogeneous equation (d^2y/dx^2) - 5(dy/dx) + 8y = 0 is:

r^2 - 5r + 8 = 0

The roots of this equation are r1 = 2 and r2 = 4.

Therefore, the general solution to the homogeneous equation is:

y_h = c1e^(2x) + c2e^(4x)

Now, we need to find a particular solution to the non-homogeneous equation.

Since the right-hand side of the equation is xex, which is a product of a polynomial and an exponential function, we can assume a particular solution of the form:

y_p = (Ax + B)ex

Taking the first and second derivatives of y_p:

y_p' = Aex + (Ax + B)ex

y_p'' = 2Aex + (Ax + B)ex

Substituting these expressions into the differential equation:

2Aex + (Ax + B)ex - 5(Aex + (Ax + B)ex) + 8(Ax + B)ex = xex

Simplifying:

(-3A + 8B)ex = xex

Therefore, we have:

-3A + 8B = x

To solve for A and B, we differentiate y_p:

y_p' = Aex + (Ax + B)ex

y_p'(0) = A + B = 0

Therefore, B = -A.

Substituting this into the equation -3A + 8B = x, we get:

-3A + 8(-A) = x

Solving for A, we get:

A = -x/5

Substituting this into B = -A, we get:

B = x/5

Therefore, the particular solution to the differential equation is:

y_p = (-x/5 + x/5)ex = (0)ex = 0

The general solution to the non-homogeneous equation is:

y = y_h + y_p = c1e^(2x) + c2e^(4x)

Therefore, the general solution to the differential equation is:

y = c1e^(2x) + c2e^(4x)
User Thesteve
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