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#### find_the_fun

##### Active member

- Feb 1, 2012

- 166

step 1)consider the definition of solution

Any function \(\displaystyle \phi\) defined on an interval I and possessing at least n derivatives that are continuous on I which when substituted into an nth-order ordinary differential equation reduces the equation to an identity, is said to be a solution of the equation on the interval

So it sounds to me like the task is to find a function that is not differentiable. Where I'm stuck is every function I know of is differentiable at some point and the question (I think) is asking for a DE that has no solutions over any interval.