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Ch. 4 - Laws of Sines and Cosines; Vectors
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601당신이 사용하는 게 아니라요?교과서 변경
4장, 문제 53

In Exercises 53–56, let u = -2i + 3j, v = 6i - j, w = -3i. Find each specified vector or scalar. 4u - (2v - w)

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Identify the given vectors: \( \mathbf{u} = -2\mathbf{i} + 3\mathbf{j} \), \( \mathbf{v} = 6\mathbf{i} - \mathbf{j} \), and \( \mathbf{w} = -3\mathbf{i} \).
Calculate \( 2\mathbf{v} \) by multiplying each component of \( \mathbf{v} \) by 2: \( 2\mathbf{v} = 2(6\mathbf{i} - \mathbf{j}) = 12\mathbf{i} - 2\mathbf{j} \).
Subtract \( \mathbf{w} \) from \( 2\mathbf{v} \): \( 2\mathbf{v} - \mathbf{w} = (12\mathbf{i} - 2\mathbf{j}) - (-3\mathbf{i}) = 12\mathbf{i} - 2\mathbf{j} + 3\mathbf{i} = 15\mathbf{i} - 2\mathbf{j} \).
Calculate \( 4\mathbf{u} \) by multiplying each component of \( \mathbf{u} \) by 4: \( 4\mathbf{u} = 4(-2\mathbf{i} + 3\mathbf{j}) = -8\mathbf{i} + 12\mathbf{j} \).
Subtract \( (2\mathbf{v} - \mathbf{w}) \) from \( 4\mathbf{u} \): \( 4\mathbf{u} - (2\mathbf{v} - \mathbf{w}) = (-8\mathbf{i} + 12\mathbf{j}) - (15\mathbf{i} - 2\mathbf{j}) = -8\mathbf{i} + 12\mathbf{j} - 15\mathbf{i} + 2\mathbf{j} = -23\mathbf{i} + 14\mathbf{j} \).

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

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Vector operations include addition, subtraction, and scalar multiplication. In this context, vectors are treated as quantities with both magnitude and direction, represented in component form. Understanding how to manipulate vectors through these operations is essential for solving problems involving multiple vectors.
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Scalar Multiplication

Scalar multiplication involves multiplying a vector by a scalar (a real number), which scales the vector's magnitude without changing its direction. For example, multiplying the vector u = -2i + 3j by a scalar 4 results in the vector -8i + 12j. This concept is crucial for transforming vectors in the given expression.
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Vector Subtraction

Vector subtraction is the process of finding the difference between two vectors, which can be visualized as adding the negative of one vector to another. For instance, subtracting vector w from 2v involves changing the direction of w and then adding it to 2v. This operation is key to simplifying the expression in the problem.
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