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### limit $\lim_{n\to ∞}\sin(\pi(2+\sqrt3)^n)$

$\lim_{n\to ∞}\sin(\pi(2+\sqrt3)^n)$ I tried to write it as $\sin (n\pi - \theta)$ to get the form $∞-∞$ form within $\sin$ function. But could not proceed after that. How should I do it? Edit:I am ...
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### How to prove that the Binet formula gives the terms of the Fibonacci Sequence?

This formula provides the $n$th term in the Fibonacci Sequence, and is defined using the recurrence formula: $u_n = u_{n − 1} + u_{n − 2}$, for $n > 1$, where $u_0 = 0$ and $u_1 = 1$. Show that ...
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### Prove $x = \sqrt{\sqrt{3} + \sqrt{2}} + \sqrt{\sqrt{3} - \sqrt{2}}$ is irrational

Prove $x = \sqrt{\sqrt{3} + \sqrt{2}} + \sqrt{\sqrt{3} - \sqrt{2}}$ is irrational. I can prove that $x$ is irrational by showing that it's a root of a polynomial with integer coefficients ...
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### The number $(3+\sqrt{5})^n+(3-\sqrt{5})^n$ is an integer

Prove by induction that this number is an integer: $$u_n=(3+\sqrt{5})^n+(3-\sqrt{5})^n$$ Progress I assumed that it holds for $n$ and I tried to do it for $n+1$ but the algebra gets quite messy and I'...