Multiply by the identity or the null

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Other lessons in this sub-strand

1. Column, row, square and rectangular
2. The null matrix and the identity
3. Add and subtract compatible matrices
4. Multiply by a scalar
5. When two matrices can be multiplied
6. Multiply two square matrices
7. A column or a row in the product
8. The order of multiplication matters
9. Multiply by the identity or the null
10. The determinant of a 2 by 2 matrix
11. A singular matrix
12. The inverse when the determinant is 1
13. Divide by the determinant, or stop
14. Two equations by the inverse
15. No unique solution
16. Prices from two purchases