Chapter 1: Problem 3
Prove that \(\frac{1}{2} \mathbf{v}+\frac{1}{2} \mathbf{v}=\mathbf{v}\)
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Chapter 1: Problem 3
Prove that \(\frac{1}{2} \mathbf{v}+\frac{1}{2} \mathbf{v}=\mathbf{v}\)
These are the key concepts you need to understand to accurately answer the question.
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Let \(X\) be any nonempty set and let \(n\) be a positive integer. Let \(V\) denote the set of all functions \(f: X \rightarrow \mathbb{R}^{n}\). Any element of \(V\) corresponds to an ordered list of functions \(f_{i}: X \rightarrow \mathbb{R}\) for \(i=1,2, \ldots, n\) such that \(f(x)=\) \(\left(f_{1}(x), f_{2}(x), \ldots, f_{n}(x)\right)\) for all \(x \in X\). Define addition and scalar multiplication on \(V\) in terms of the corresponding operations on the coordinate functions. Show that with these operations, \(V\) is a vector space.
Is it possible to add two sets? For sets of real numbers, we might define addition of sets in terms of addition of the elements in the sets. Let us introduce the following meaning to the symbol \(\oplus\) for adding a set \(A\) of real numbers to another set \(B\) of real numbers: \(A \oplus B=\\{a+b \mid a \in A\) and \(b \in B\\}\). a. List the elements in the set \(\\{1,2,3\\} \oplus\\{5,10\\}\). b. List the elements in the set \(\\{1,2,3\\} \oplus\\{5,6\\}\). c. List the elements in the set \(\\{1,2,3\\} \oplus \varnothing\). d. If a set \(A\) contams \(m\) real numbers and a set \(B\) contains \(n\) real numbers, can you predict the number of elements in \(A \oplus B\) ? If you run into difficulties, can you determine the minimum and naximum numbers of elements possible in \(A \oplus B\) ? e. Does the commutative law hold for this new addition? That is, does \(A \oplus\) \(B=B \oplus A\) ? f. Reformulate other laws of real-number addition in terms of this new addition of sets. Which of your formulas are true? Can you prove them or provide counterexamples? g. What about laws that combine set addition with union and intersection? For example, does \((A \cup B) \oplus C=(A \oplus C) \cup(B \oplus C)\) ? h. Is there any hope of extending the other operations of arithmetic to sets of real numbers? What about algebra? Limits? Power series?
Determine whether we obtain a vector space from \(\mathbb{R}^{2}\) with operations defined by $$ \begin{aligned} \left(v_{1}, v_{2}\right)+\left(w_{1}, w_{2}\right) &=\left(v_{1}+w_{1}, v_{2}+w_{2}+1\right) \\ r\left(v_{1}, v_{2}\right) &=\left(r v_{1}, r_{2}\right) \end{aligned} $$ Notice that the additive identity vector is \((0,-1)\) since $$ \begin{aligned} \left(v_{1}, v_{2}\right)+(0,-1) &=\left(v_{1}+0, v_{2}+(-1)+1\right) \\ &=\left(v_{1}, v_{2}\right) \end{aligned} $$ as required by Axiom \(3 .\)
Write the \(y\)-axis as a line in \(\mathbb{R}^{2}\).
Write the line in \(\mathbb{R}^{2}\) that is tangent to the unit circle at the point \(\left(\frac{1}{\sqrt{2}}, \frac{1}{\sqrt{2}}\right)\) in the form \(\\{r+x \mid r \in \mathbb{R}\\}\). (Suggestion: The tangent line will intersect the axes at points \((a, 0)\) and \((0, a)\) equidistant from the origin. You do not need to know the value of \(a\) to find a direction vector.)
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