Chapter 4: Problem 7
Evaluate each of the following: (a) \(\sum_{i=1}^{33} i ;\) (b) \(\sum_{i=11}^{32} i^{2}\).
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Chapter 4: Problem 7
Evaluate each of the following: (a) \(\sum_{i=1}^{33} i ;\) (b) \(\sum_{i=11}^{32} i^{2}\).
These are the key concepts you need to understand to accurately answer the question.
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For \(a, b \in \mathbf{Z}^{+}\)and \(s, t \in \mathbf{Z}\), what can we say about \(\operatorname{gcd}(a, b)\) if a) \(a s+b t=2\) ? b) \(a s+b t=3\) ? c) \(a s+b t=4\) ? d) \(a s+b t=6\) ?
One can use the Well-Ordering Principle to provide an alternate proof that \(\sqrt{2}\) is irrational. Assume that \(\sqrt{2}\) is rational and consider the (nonempty) set \(S \subseteq \mathbf{Z}^{*}\) where \(S=\left\\{a \mid a \sqrt{2} \in \mathbf{Z}^{+}\right\\}\). Then use this set \(S\) to obtain a contradiction.
For any \(n \in \mathbf{Z}, n \geq 0\), prove that a) \(2^{2 n+1}+1\) is divisible by \(3 .\) b) \(n^{3}+(n+1)^{3}+(n+2)^{3}\) is divisible by \(9 .\) c) \(\frac{n^{7}}{7}+\frac{n^{3}}{3}+\frac{11 n}{21}\) is an integer.
If \(a, x, y \in \mathbf{Z}\), and \(a \neq 0\), prove that \(a x=a y \Rightarrow x=y\).
Consider the following six equations. $$ \begin{array}{r} 1) \\ 2) \\ 3) \\ 4) \\ 5) \\ 6) \end{array} $$$$ \begin{aligned} 1 &=1 \\ 1-4 &=-(1+2) \\ 1-4+9 &=1+2+3 \\ 1-4+9-16 &=-(1+2+3+4) \\ 1-4+9-16+25 &=1+2+3+4+5 \\ 1-4+9-16+25-36 &=-(1+2+3+4+5+6) \end{aligned} $$ Conjecture the general formula suggested by these six equations, and prove your conjecture.
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