Mathematics — first biennium · Lesson
In the product AB each entry comes from the dot product of a row of A and a column of B. It is not entry-by-entry multiplication.
Prerequisites: Matrix operations and dot product
Goal: Multiply two 2×2 matrices using the row-by-column rule and distinguish AB from BA.
In this lesson: Multiply two 2×2 matrices using the row-by-column rule and distinguish AB from BA.
New concept: In the product AB, each entry of the result is the dot product of a row of A with a column of B. The product is defined only when the number of columns of A equals the number of rows of B; in general AB≠BA.
How to proceed: For (1,2), take the first row of A and the second column of B. Write the two products before adding them.
You can already assume: Matrix operations and dot product.
Completed exercises: 0/5 · Correct on first attempt: 0
For (1,2), take the first row of A and the second column of B. Write the two products before adding them.
Data / situation: Calculate the requested entries of AB for A=[[1,-2],[-3,0]] and B=[[-3,0],[-1,3]].
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