Chapter 4: Problem 7
Does \(\lim _{n \rightarrow \infty}\left(\frac{1+1}{\sqrt{2}}\right)^{n}\) exist? Why?
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Chapter 4: Problem 7
Does \(\lim _{n \rightarrow \infty}\left(\frac{1+1}{\sqrt{2}}\right)^{n}\) exist? Why?
These are the key concepts you need to understand to accurately answer the question.
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Prove that a sequence can have only one limit. Hint: Suppose that there is a sequence \(\left\\{z_{n}\right\\}\) such that \(z_{n} \rightarrow \zeta_{1}\) and \(z_{n} \rightarrow \zeta_{2}\). Show this implies \(\zeta_{1}=\zeta_{2}\) by proving that for all \(\varepsilon>0,\left|\zeta_{1}-\zeta_{2}\right|<\varepsilon\).
Prove that Newton's method always works for polynomials of degree 1 (functions of the form \(f(z)=a z+b\), where \(a \neq 0\) ). How many iterations are necessary before Newton's method produces the solution \(z=-\frac{1}{a}\) to \(f(z)=0 ?\)
Let \(z_{n}=r_{n} e^{i \theta_{n}} \neq 0\), where \(\theta_{n}=\operatorname{Arg}\left(z_{n}\right)\). (a) Suppose \(\lim _{n \rightarrow \infty} r_{n}=r_{0}\) and \(\lim _{n \rightarrow \infty} \theta_{n}=\theta_{0} .\) Show \(\lim _{n \rightarrow \infty} r_{n} e^{i \theta_{n}}=r_{0} e^{i \theta_{0}}\) (b) Find an example where \(\lim _{n \rightarrow \infty} z_{n}=z_{0}=r_{0} e^{i \theta_{0}}, \lim _{n \rightarrow \infty} r_{n}=r_{0}\), but \(\lim _{n \rightarrow \infty} \theta_{n}\) does not exist. (c) Is it possible to have \(\lim _{n \rightarrow \infty} z_{n}=z_{0}=r_{0} e^{i \theta_{0}}\), but \(\lim _{n \rightarrow \infty} r_{n}\) does not exist?
In the geometric series, show that if \(|z|>1\), then \(\lim _{n \rightarrow \infty}\left|S_{n}\right|=\infty\).
Let \(\sum_{k=1}^{\infty}\left(x_{n}+i y_{n}\right)=u+i v .\) If \(c=a+i b\) is a complex constant, show that \(\sum_{n=1}^{\infty}(a+i b)\left(x_{n}+i y_{n}\right)=(a+i b)(u+i v)\)
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