Quick Question on Variation of Parameters Differential Equations

colonelone
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Homework Statement



What do you do if one of the roots to the characteristic equation of a differential equation is zero when using variation of parameters?

Homework Equations


The Attempt at a Solution



The problem I encountered this in is

y" - y' = 4t

Characteristic equation

r2 - r = 0

so

r = -1 , 0

Therefore

y1 = e-t

but

y2 = 0

which would make the Wronskian zero.

Any thoughts?
 
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Your other solution would be y2=e^(0*t) = 1
 
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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