Chapter 8: Problem 10
Let \(g_{n}(x):=e^{-n x} / n\) for \(x \geq 0, n \in \mathbb{N}\). Examine the relation between \(\lim \left(g_{n}\right)\) and \(\lim \left(g_{n}^{\prime}\right)\).
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Chapter 8: Problem 10
Let \(g_{n}(x):=e^{-n x} / n\) for \(x \geq 0, n \in \mathbb{N}\). Examine the relation between \(\lim \left(g_{n}\right)\) and \(\lim \left(g_{n}^{\prime}\right)\).
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Evaluate \(\lim \left(x^{n} /\left(1+x^{n}\right)\right)\) for \(x \in \mathbb{R}, x \geq 0\)
Let \(a_{k}>0\) for \(k=1, \cdots, n\) and let \(A:=\left(a_{1}+\cdots+a_{n}\right) / n\) be the arithmetic mean of these numbers. For each \(k\), put \(x_{k}:=a_{k} / A-1\) in the inequality \(1+x \leq e^{x}(\) valid for \(x \geq 0)\). Multiply the resulting terms to prove the Arithmetic-Geometric Mean Inequality (6) $$ \left(a_{1} \cdots a_{n}\right)^{1 / n} \leq \frac{1}{n}\left(a_{1}+\cdots+a_{n}\right) $$ Moreover, show that equality holds in \((6)\) if and only if \(a_{1}=a_{2}=\cdots=a_{n}\).
Show that if \(x>0\) and if \(n>2 x\), then
$$
\left|e^{x}-\left(1+\frac{x}{1 !}+\cdots+\frac{x^{n}}{n
!}\right)\right|<\frac{2 x^{n+1}}{(n+1) !}
$$
Use this formula to show that \(2 \frac{2}{3}
Show that \(\lim \left(n x /\left(1+n^{2} x^{2}\right)\right)=0\) for all \(x \in \mathbb{R}\).
Calculate \(\pi\) by approximating the smallest positive zero of sin. (Either bisect intervals or use Newton's Method of Section 6.4.)
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