In Exercises 47–52, write the vector v in terms of i and j whose magnitude ||v|| and direction angle θ are given. ||v|| = 12, θ = 225°
Ch. 4 - Laws of Sines and Cosines; Vectors

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.
Vector Operations
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.
추천 영상:
Algebraic Operations on Vectors
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.
추천 영상:
Multiplying Vectors By Scalars
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.
추천 영상:
Adding Vectors Geometrically
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