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SL diff eqn

d2ydx2+λy=0,  x[0,π][br]1.y(0)=0[br]2.y(π)+y(π)=0\dfrac{d^2 y}{dx^2} + \lambda y = 0 , \ \ x \in [0, \pi] [br]\\ 1. y(0) = 0 [br]\\ 2. y'(\pi)+y(\pi)=0

Working



I'm asked to show that there exists an infinite sequence of positive eigenvalues (this is fine, each value of α\alpha is reflected in y=-x on the graph and presto, we have countably infinite evalues in Z0\mathbb{Z}_{\geq0}).

Then, I'm asked to show that the smallest eigenvalue λ1\lambda_1 is such that 14<λ1<1\dfrac{1}{4} < \lambda_1 < 1, whereas I've simply found it to be 12<λ1<1\dfrac{1}{2} < \lambda_1 < 1. I'm not sure what I've done wrong here.

Secondly, as n becomes large, λn(n12)2\lambda_n \rightarrow (n-\frac{1}{2})^2... I'd have thought this was simply because each value of αn\alpha_n essentially "tends to" (for lack of a better phrase) n12n - \frac{1}{2}, and since λn=αn2 \lambda_n = \alpha_n^2 , we have λn(n12)2\lambda_{n} \approx {(n - \frac{1}{2})}^2...?

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