Chapter 12: Problem 6
In Exercises \(1-8,\) let \(\mathbf{u}=\langle 3,-2\rangle\) and \(\mathbf{v}=\langle- 2,5\rangle .\) Find the (a) component form and \((\mathbf{b})\) magnitude (length) of the vector. $$ -2 \mathbf{u}+5 \mathbf{v} $$
Short Answer
Expert verified
The component form is \( \langle -16, 29 \rangle \), and the magnitude is approximately 33.1.
Step by step solution
01
Scale vector \( \mathbf{u} \)
Multiply vector \( \mathbf{u} = \langle 3, -2 \rangle \) by \(-2\). This involves multiplying each component of \( \mathbf{u} \) by \(-2\):\[-2 \times \mathbf{u} = \langle -2 \times 3, -2 \times (-2) \rangle = \langle -6, 4 \rangle.\]
02
Scale vector \( \mathbf{v} \)
Multiply vector \( \mathbf{v} = \langle -2, 5 \rangle \) by \(5\). This involves multiplying each component of \( \mathbf{v} \) by \(5\):\[5 \times \mathbf{v} = \langle 5 \times (-2), 5 \times 5 \rangle = \langle -10, 25 \rangle.\]
03
Add scaled vectors
Add the results of the two scaled vectors from Steps 1 and 2 to find \(-2 \mathbf{u} + 5 \mathbf{v}\):\[-2 \mathbf{u} + 5 \mathbf{v} = \langle -6, 4 \rangle + \langle -10, 25 \rangle = \langle -6 + (-10), 4 + 25 \rangle = \langle -16, 29 \rangle.\]
04
Calculate the magnitude
Find the magnitude (length) of the vector \( \langle -16, 29 \rangle \) using the formula \( ||\mathbf{a}|| = \sqrt{a_1^2 + a_2^2} \).\[||\langle -16, 29 \rangle|| = \sqrt{(-16)^2 + 29^2} = \sqrt{256 + 841} = \sqrt{1097} = \approx 33.1.\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Vector Addition
In the world of mathematics education, vector addition is a fundamental operation involving two or more vectors. To add vectors, you simply add their corresponding components. For example, suppose we have two vectors \( \mathbf{a} = \langle a_1, a_2 \rangle \) and \( \mathbf{b} = \langle b_1, b_2 \rangle \). The sum \( \mathbf{a} + \mathbf{b} \) is found by:
Remember, vector addition is a component-wise action that makes combining vector quantities intuitive and efficient.
- Adding the respective components: \( a_1 + b_1 \) and \( a_2 + b_2 \).
Remember, vector addition is a component-wise action that makes combining vector quantities intuitive and efficient.
Vector Scaling
Vector scaling is a vector operation that involves multiplying a vector by a scalar (a real number). When performing vector scaling, you multiply each component of a vector by the scalar value.
For example, if you have a vector \( \mathbf{v} = \langle v_1, v_2 \rangle \) and a scalar \( k \), the scaled vector is given by:
For example, if you have a vector \( \mathbf{v} = \langle v_1, v_2 \rangle \) and a scalar \( k \), the scaled vector is given by:
- \( k \times \mathbf{v} = \langle k \times v_1, k \times v_2 \rangle \).
Magnitude of a Vector
The magnitude of a vector is a measure of its length. You can calculate it using the Pythagorean theorem, which provides a way to find the distance from the origin in a Cartesian coordinate system.
If a vector \( \mathbf{a} = \langle a_1, a_2 \rangle \), its magnitude \( ||\mathbf{a}|| \) can be determined by the formula:
This concept sits at the core of vector analysis, helping bridge the understanding of geometric and algebraic properties of vectors.
If a vector \( \mathbf{a} = \langle a_1, a_2 \rangle \), its magnitude \( ||\mathbf{a}|| \) can be determined by the formula:
- \( \sqrt{a_1^2 + a_2^2} \).
This concept sits at the core of vector analysis, helping bridge the understanding of geometric and algebraic properties of vectors.
Mathematics Education
Mathematics education pertaining to vector operations plays a critical role in building foundational skills in mathematics and physics. Students learn about vectors in a progression:
Providing simple exercises, relatable examples, and step-by-step guidance ensures that students grasp vector operations effectively and with confidence.
- Introducing basic vector notation and operations like addition and multiplication.
- Developing an understanding of geometric concepts through vector diagrams.
- Exploring real-world applications such as engineering, robotics, and physics simulations.
Providing simple exercises, relatable examples, and step-by-step guidance ensures that students grasp vector operations effectively and with confidence.