Practice question · Select all that apply
Let A be 3x2 and B be 2x3. Select every statement that is TRUE.
Hints
- Check inner dimensions for each product; check identical shape for the sum.
- A(3x2) times B(2x3): inner 2 = 2, result outer 3x3. B(2x3) times A(3x2): inner 3 = 3, result 2x2.
Show the answer
- A. BA is defined
- B. AB is defined
- C. AB is 3x3
- E. BA is 2x2
Why
AB has inner dimensions 2 = 2 and result 3x3; BA has inner 3 = 3 and result 2x2, both defined. A + B needs identical shapes, but 3x2 and 2x3 differ, so the sum is undefined.
Practise Matrices and Matrix Operations
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