InterviewSolution
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InterviewSolution
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If `A=[{:(2,-1),(3,4),(1,5):}]" and "B=[{:(-1,3),(2,1):}]`, find AB. Does BA exist? |
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Answer» Here A is a `3xx2` matrix and B is a `2xx2` matrix. Clearly, the number of columns in A equals the number of rows in B. `:.` AB exists and it is a `3xx2` matrix. Now, `AB=[{:(2,-1),(3,4),(1,5):}][{:(-1,3),(2,1):}]` `=[{:(2.(-1)+(-1).2,2.3+(-1).1),(3.(-1)+4.2,3.3+4.1),(1.(-1)+5.2,1.3+5.1):}]` `=[{:(-4,5),(5,13),(9,8):}].` Further, B is a `2xx2` matrix and A is a `3xx2` matrix. So, the number of columns in B is not equal to the number of rows in A. So, BA does not exist. |
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