First Order Linear Nonhomogenous Differential Equation

IBY
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A question, if you have a nonhomogenous first order differential equation, can it be solved by using the usual nonhomogenous way, with the arbitrary constants, instead of using the integrating factor?
 
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You can use variation of parameters or method of superposition
 
The question did NOT state that the equation was linear and both "variation of parameters" and the "method of superposition" require that the equation be linear.
 
So, let's take the following:
Ay'+By=C

I know its solution is: \frac{C}{B}(1-e^{-t\frac{B}{A}})

For the homogenous part:
Ay'+By=0
Characteristic equation is:
Ak+B=0
k=-\frac{B}{A}

So the solution for the homogenous part is:
y=e^{-t\frac{B}{A}}

Now, from what I have read about variation of parameters, there is a function v such that:
Y=vy
Y'=v'y+vy'

So, would that be:
vBe^{-t\frac{B}{A}}=Y
v'Be^{-t\frac{B}{A}}-v\frac{B^2}{A}e^{-t\frac{B}{A}}=Y'

Err... Correct?
 
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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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