If A has rows (3, -3) and (3, -1) and B has rows (-3, 4) and (3, 2), find the entry in row 2, column 1 of AB.
Answer and explanation
Correct answer: B.
- Step 1: The entry is (row 2 of A) · (column 1 of B). Step 2. (3)(-3) + (-1)(3) = -12. **Answer: . Why not the others:** is what you get if you multiply the entries by rows of B instead of columns. is what you get if you multiply the matching entries. does not fit.
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