/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 8 Show that, for any vector \(\lef... [FREE SOLUTION] | 91Ó°ÊÓ

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Show that, for any vector \(\left[\begin{array}{l}p \\ q \\\ r\end{array}\right]\), constants \(\alpha, \beta, \gamma \mathrm{can}\) always be found so that $$ \left[\begin{array}{c} p \\ q \\ r \end{array}\right]=\alpha\left[\begin{array}{l} 1 \\ 1 \\ 0 \end{array}\right]+\beta\left[\begin{array}{l} 1 \\ 0 \\ 1 \end{array}\right]+\gamma\left[\begin{array}{l} 0 \\ 1 \\ 1 \end{array}\right] $$ Note: Exercises \(7(\mathrm{~b})\) and 8 are special cases of a general result that given three \(3 \times 1\) linearly independent vectors \(\boldsymbol{a}, \boldsymbol{b}, \boldsymbol{c}\) then any \(3 \times 1\) vector can be written \(\alpha \boldsymbol{a}+\beta \boldsymbol{b}+\gamma \boldsymbol{c}\) ).

Short Answer

Expert verified
Constants \(\alpha, \beta, \gamma\) always exist and can be solved as functions of \(p, q, r\).

Step by step solution

01

Set Up the Equation

Begin by equating the vector \(\begin{bmatrix} p \ q \ r \end{bmatrix}\) to the given linear combination of vectors: \[ \begin{bmatrix} p \ q \ r \end{bmatrix} = \alpha \begin{bmatrix} 1 \ 1 \ 0 \end{bmatrix} + \beta \begin{bmatrix} 1 \ 0 \ 1 \end{bmatrix} + \gamma \begin{bmatrix} 0 \ 1 \ 1 \end{bmatrix}. \] Expand the right side to form one vector expression.
02

Expand and Collect Terms

Expand the expression on the right side: \[ \alpha \begin{bmatrix} 1 \ 1 \ 0 \end{bmatrix} + \beta \begin{bmatrix} 1 \ 0 \ 1 \end{bmatrix} + \gamma \begin{bmatrix} 0 \ 1 \ 1 \end{bmatrix} = \begin{bmatrix} \alpha + \beta \ \alpha + \gamma \ \beta + \gamma \end{bmatrix}. \] This combines each component linearly.
03

Match Components

Set the components on both sides of the equation equal to each other: 1. \(p = \alpha + \beta\)2. \(q = \alpha + \gamma\)3. \(r = \beta + \gamma\)Relate these to find \(\alpha, \beta, \gamma\).
04

Solve for \(\alpha, \beta, \gamma\)

Solve the system of equations:1. From \(\alpha + \beta = p\), express \(\beta = p - \alpha\).2. From \(\alpha + \gamma = q\), express \(\gamma = q - \alpha\).3. Substitute into \(\beta + \gamma = r\): - \((p - \alpha) + (q - \alpha) = r\) - \(p + q - 2\alpha = r\) - \(2\alpha = p + q - r\) - \(\alpha = \frac{p + q - r}{2}\)4. Substitute back to find \(\beta = p - \alpha\) and \(\gamma = q - \alpha\).
05

Final Result

Since \(\alpha = \frac{p + q - r}{2} \), \(\beta = p - \frac{p + q - r}{2} \), and \(\gamma = q - \frac{p + q - r}{2} \), we have verified that constants \(\alpha, \beta, \gamma\) can always be found for any given vector \(\begin{bmatrix} p \ q \ r \end{bmatrix}\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Linear Independence
Linear independence is a fundamental concept in vector spaces, crucial for understanding vector decomposition. A set of vectors is said to be linearly independent if no vector in the set can be written as a linear combination of the others. In simpler terms, each vector provides a unique direction in the vector space, and none of them is redundant.

To visualize this, imagine having two vectors in a plane. If these vectors are linearly independent, they point in different directions and are not a mere scaling of one another. Now, in the exercise, the vectors \(\begin{bmatrix} 1 \ 1 \ 0 \end{bmatrix}\), \(\begin{bmatrix} 1 \ 0 \ 1 \end{bmatrix}\), and \(\begin{bmatrix} 0 \ 1 \ 1 \end{bmatrix}\) are linearly independent. None can be expressed as a combination of the other two, meaning they span a 3-dimensional space, which is necessary for any vector in \(\mathbb{R}^3\) to be expressed as a linear combination of these vectors.

Knowing that a set of vectors is linearly independent helps us confirm that we can find coefficients \(\alpha, \beta, \gamma\) to express any vector \(\begin{bmatrix} p \ q \ r \end{bmatrix}\) using these vectors.
Vector Spaces
A vector space is a collection of objects called vectors, which can be added together and multiplied by scalars. These spaces, also known as linear spaces, follow specific rules or axioms, such as closure under addition and scalar multiplication, existence of a zero vector, etc. This means that if you add two vectors or scale a vector within the vector space, you will still be within the vector space.

The vectors \(\begin{bmatrix} 1 \ 1 \ 0 \end{bmatrix}\), \(\begin{bmatrix} 1 \ 0 \ 1 \end{bmatrix}\), and \(\begin{bmatrix} 0 \ 1 \ 1 \end{bmatrix}\) form a vector space in this exercise. When combined linearly — by scaling and adding — these vectors can produce any vector in \(\mathbb{R}^3\). This ability to generate or 'span' the entire space of \(\mathbb{R}^3\) from these three vectors is possible because they are linearly independent, forming a basis for the vector space.

Understanding vector spaces helps us grasp how vectors can interact within a geometric framework and gives us the tools to manipulate vectors in multidimensional spaces.
Linear Combinations
Linear combinations involve creating a new vector by scaling and adding a set of vectors. This comes into play when expressing one vector as a combination of others, which is a core ability in vector decomposition.

In the original exercise, we were tasked with expressing \(\begin{bmatrix} p \ q \ r \end{bmatrix}\) as a linear combination of the vectors \(\begin{bmatrix} 1 \ 1 \ 0 \end{bmatrix}\), \(\begin{bmatrix} 1 \ 0 \ 1 \end{bmatrix}\), and \(\begin{bmatrix} 0 \ 1 \ 1 \end{bmatrix}\). The expression \(\alpha \begin{bmatrix} 1 \ 1 \ 0 \end{bmatrix} + \beta \begin{bmatrix} 1 \ 0 \ 1 \end{bmatrix} + \gamma \begin{bmatrix} 0 \ 1 \ 1 \end{bmatrix}\) represents this linear combination. Each constant \(\alpha\), \(\beta\), and \(\gamma\) represents how much of each vector contributes to the final result.

Seeing a vector as a linear combination of others not only aids in vector decomposition but also is crucial in data analysis, physics, computer graphics, and many other fields. By mastering linear combinations, you're equipped to solve complex problems involving vector transformation and manipulation.

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Most popular questions from this chapter

A function is known to fit closely to the approximate function $$ f(z)=\frac{a z+b}{c z+1} $$ It is fitted to the three points \((z=0, f=1),(z=0.5\), \(f=1.128\) ) and \((z=1.3, f=1.971)\). Show that the parameters satisfy $$ \left[\begin{array}{l} 1 \\ 1.128 \\ 1.971 \end{array}\right]=\left[\begin{array}{lll} 0 & 1 & 0 \\ 0.5 & 1 & -0.5640 \\ 1.3 & 1 & -2.562 \end{array}\right]\left[\begin{array}{l} a \\ b \\ c \end{array}\right] $$ Find \(a, b\) and \(c\) and hence the approximating function (use of MATLAB is recommended). Check the value \(f(1)=1.543\). (Note that the values were chosen from tables of \(\cosh z\).) The method described here is a simple example of a powerful approximation method.

A computer screen has dimensions \(20 \mathrm{~cm} \times 30 \mathrm{~cm}\). Axes are set up at the centre of the screen, as illustrated in Figure 5.5. A box containing an arrow, has dimensions \(2 \mathrm{~cm} \times 2 \mathrm{~cm}\) and is situated with its centre at the point \((-16,10)\). It is first to be rotated through \(45^{\circ}\) in an anticlockwise direction. Find this transformation in the form $$ \left[\begin{array}{c} x^{\prime}+16 \\ y^{\prime}-10 \end{array}\right]=\boldsymbol{A}\left[\begin{array}{c} x+16 \\ y-10 \end{array}\right] $$

Find a series of row manipulations that takes \(\left|\begin{array}{lll}1 & 0 & 1 \\ 2 & 1 & 0 \\ 0 & 1 & 1\end{array}\right|\) to \(-\left|\begin{array}{lrl}2 & 1 & 0 \\ 0 & -\frac{1}{2} & 1 \\ 0 & 0 & 3\end{array}\right|\) and hence evaluate the determinant.

Given the matrix $$ \boldsymbol{A}=\left[\begin{array}{llllllll} 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 \\ 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 \\ 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 \\ 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 \\ 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 \\ 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 \\ 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 \end{array}\right] $$ it is known that \(\boldsymbol{A}^{n}=\boldsymbol{I}\), the unit matrix, for some integer \(n\); find this value.

Let $$ \boldsymbol{A}=\left[\begin{array}{rr} -1 & 2 \\ 4 & 1 \end{array}\right] \text { and } \quad \boldsymbol{B}=\left[\begin{array}{ll} 1 & 1 \\ \lambda & \mu \end{array}\right] $$ where \(\lambda \neq \mu\). Find all pairs of values \(\lambda, \mu\) such that \(\boldsymbol{B}^{-1} \boldsymbol{A} \boldsymbol{B}\) is a diagonal matrix.

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