Determining Existence and Uniqueness

Ian Baughman
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Homework Statement



Determine whether existence of at least one solution of the given initial value problem is guaranteed and, if so, whether uniqueness of the solution is guaranteed.

dy/dx=y^(1/3); y(0)=0

Homework Equations



Existence and Uniqueness of Solutions Theorem:

Suppose that both the function ƒ(x,y) and its partial derivative [D][/y]f(x,y) are continuous on some rectangle R in the xy-plane that contains the point (a,b) in its interior. Then, for some open interval I containing the point a, the initial value problem

dy/dx=ƒ(x,y), y(a)=b

has one and only one solution that is defined on the interval I.

The Attempt at a Solution

 
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Ian Baughman said:

Homework Statement



Determine whether existence of at least one solution of the given initial value problem is guaranteed and, if so, whether uniqueness of the solution is guaranteed.

dy/dx=y^(1/3); y(0)=0

Homework Equations



Existence and Uniqueness of Solutions Theorem:

Suppose that both the function ƒ(x,y) and its partial derivative [D][/y]f(x,y) are continuous on some rectangle R in the xy-plane that contains the point (a,b) in its interior. Then, for some open interval I containing the point a, the initial value problem

dy/dx=ƒ(x,y), y(a)=b

has one and only one solution that is defined on the interval I.

The Attempt at a Solution


So, what have you tried? You have to show some effort in this forum. Does the theorem apply to your problem? Have you looked for solution(s)? Show us what you are thinking...
 
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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