Matrices Question
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Grade 12 Matrices CCSS: HSN-VM.C.9
In Leane's math homework, she has to multiply three matrices together by hand, as follows: [820-47-3]⋅[47-4-21387-5-366]⋅[-65-41]. She decides that if she multiplies the last two matrices together first, it will make the computation easier. Is she correct? Why or why not.
- No, she cannot do this. She has to multiply the first two matrices together first, and then the third, according to normal evaluating rules.
- Although she is allowed to do this, it will not make the computation easier. Regardless of how she multiplies these matrices, the answer will be a 2-by-1 matrix, and the same work will be involved either way.
- Yes, she can do this, and it will make the computation easier. Multiplying the second and third matrices together first, and then the first by the product just found, will reduce the total number of arithmetic computations (multiplication and addition) to be performed.
- These matrices are not able to be multiplied together, as they have incompatible dimensions.