Find a × b for a = 3i + 4j − 1k and b = 2i − 2j + 3k.
Answer and explanation
Correct answer: A. 10i − 11j − 14k
- Step 1: Use the determinant with rows (i, j, k), (a₁, a₂, a₃), (b₁, b₂, b₃). Step 2. Expanding gives 10i − 11j − 14k. Answer: 10i − 11j − 14k. Why not the others: -10i + 11j + 14k is what you get if you reverse the order of the cross product. 10i + 11j − 14k is what you get if you forget the minus sign on the j component. 6i − 8j − 3k is what you get if you multiply matching components.
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