Intro to Differential Equations Problem #1

JosephK
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Homework Statement


1. Find the general solution to the differential equation:
y''-5y'+6y = 0


Homework Equations





The Attempt at a Solution


m^2 - 5m + 6 = 0
(m-1)(m-5) = 0
y' = Ae^x+Be^5x
 
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JosephK said:

Homework Statement


1. Find the general solution to the differential equation:
y''-5y'+6y = 0


Homework Equations





The Attempt at a Solution


m^2 - 5m + 6 = 0
(m-1)(m-5) = 0
Your factorization is incorrect. (m - 1)(m - 5) = m2 - 6m + 5, not m2 - 5m + 6.
JosephK said:
y' = Ae^x+Be^5x
 
This cannot be factored.
 
JosephK said:
This cannot be factored.
(m - 3)(m - 2) ?
 
So the answer to this differential equation is

y = c1e^3x+c2e^2x?
 
Yes, and you can check for yourself that your solution satisfies the differential equation. It's always a good idea to check.
 
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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