Math Problem Statement

if vector a = 2i+3j+4k and vector b = 7i+8j-6k find a x b

Solution

To find the cross product a×b\mathbf{a} \times \mathbf{b} of two vectors a=2i+3j+4k\mathbf{a} = 2\mathbf{i} + 3\mathbf{j} + 4\mathbf{k} and b=7i+8j6k\mathbf{b} = 7\mathbf{i} + 8\mathbf{j} - 6\mathbf{k}, you can use the following determinant formula:

\begin{vmatrix} \mathbf{i} & \mathbf{j} & \mathbf{k} \\ 2 & 3 & 4 \\ 7 & 8 & -6 \end{vmatrix}$$ This determinant expands as: $$\mathbf{a} \times \mathbf{b} = \mathbf{i} \left( 3 \cdot (-6) - 4 \cdot 8 \right) - \mathbf{j} \left( 2 \cdot (-6) - 4 \cdot 7 \right) + \mathbf{k} \left( 2 \cdot 8 - 3 \cdot 7 \right)$$ Now, calculate each component: - The $$\mathbf{i}$$ component: $$3 \cdot (-6) - 4 \cdot 8 = -18 - 32 = -50$$ - The $$\mathbf{j}$$ component: $$2 \cdot (-6) - 4 \cdot 7 = -12 - 28 = -40$$ - The $$\mathbf{k}$$ component: $$2 \cdot 8 - 3 \cdot 7 = 16 - 21 = -5$$ Thus, the cross product $$\mathbf{a} \times \mathbf{b}$$ is: $$\mathbf{a} \times \mathbf{b} = -50\mathbf{i} + 40\mathbf{j} - 5\mathbf{k}$$ Or in vector form: $$\mathbf{a} \times \mathbf{b} = -50\mathbf{i} + 40\mathbf{j} - 5\mathbf{k}$$ Would you like more details on any part of this solution or have any questions? Here are some related questions to explore: 1. How do you find the magnitude of the cross product $$\mathbf{a} \times \mathbf{b}$$? 2. What is the physical interpretation of the cross product? 3. How do you verify that $$\mathbf{a} \times \mathbf{b}$$ is perpendicular to both $$\mathbf{a}$$ and $$\mathbf{b}$$? 4. What is the cross product of $$\mathbf{a}$$ with itself? 5. How does the cross product relate to the area of a parallelogram formed by two vectors? **Tip:** Remember that the cross product results in a vector that is perpendicular to the plane formed by the original vectors.

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Math Problem Analysis

Mathematical Concepts

Vectors
Cross Product

Formulas

Cross product determinant formula

Theorems

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Suitable Grade Level

Advanced High School