If A has rows (-3, 4) and (2, 3) and B has rows (-1, -3) and (-3, 4), find the entry in row 2, column 1 of AB.
Answer and explanation
Correct answer: A.
- Step 1: The entry is (row 2 of A) · (column 1 of B). Step 2. (2)(-1) + (3)(-3) = -11. **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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