Find a × b for a = 0i + 1j − 2k and b = -3i + 3j + 4k.
Answer and explanation
Correct answer: C. 10i + 6j + 3k
- Step 1: Use the determinant with rows (i, j, k), (a₁, a₂, a₃), (b₁, b₂, b₃). Step 2. Expanding gives 10i + 6j + 3k. Answer: 10i + 6j + 3k. Why not the others: -10i − 6j − 3k is what you get if you reverse the order of the cross product. 10i − 6j + 3k is what you get if you forget the minus sign on the j component. 0i + 3j − 8k is what you get if you multiply matching components.
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