Finding a particular solution for y''+4y=20sec(2t)

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SUMMARY

The discussion focuses on finding a particular solution for the differential equation y'' + 4y = 20sec(2t). The characteristic equation yields complex roots, leading to the complementary solution yc(t) = Asin(2t) + Bcos(2t). The proposed particular solution yp(t) involves integration by parts and the use of secant and tangent functions, specifically integrating terms like 10sin(2t)sec(2t) and 10cos(2t)sec(2t). The user seeks clarification on the correct application of the Wronskian in their solution process.

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Homework Statement


Find a particular solution to:

y''+4y=20sec(2t)


Homework Equations





The Attempt at a Solution


y''+4y=0
r^2+4=0
r=+or- 2i

So, yc(t) = Asin(2t) + Bcos(2t)
yp(t)= -cos(2t) ∫ 10sin(2t)sec(2t)dt + sin(2t) ∫ 10cos(2t)sec(2t)dt
= -10cos(2t) ∫ tan(2t)dt+10sin(2t) ∫ 1dt
= -10cos(2t)(-.5ln(cos(2t)))+10tsin(2t)

I don't know what's wrong. Can anyone help me out?
 
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I don't know if you did it in your integrands but did you happen to divide R(x)y1(x) by W(y1,y2) where W is the wronskian ?
 

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