Variation of parameters- 2nd order linear equation

hahaha158
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Homework Statement


solve 4y''-4y'+y=16et/2


Homework Equations



v1= -∫ y2g/w
v2= ∫ y1g/w

The Attempt at a Solution



http://imgur.com/gxXlfdH

the correct answer is 2t^2 e^(t/2) instead of what i have though, i am not sure what i am doing wrong?
 
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hahaha158 said:

Homework Statement


solve 4y''-4y'+y=16et/2


Homework Equations



v1= -∫ y2g/w
v2= ∫ y1g/w

The Attempt at a Solution



http://imgur.com/gxXlfdH

the correct answer is 2t^2 e^(t/2) instead of what i have though, i am not sure what i am doing wrong?

You need to divide by the coefficient of y'' before you start:
<br /> y&#039;&#039; - y&#039; + \frac14 y = 4e^{t/2} \equiv g(t).<br />
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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