Adding, scaling, multiplying and transposing matrices
Add and subtract matrices of the same order, multiply by a scalar, multiply row by column, and turn rows into columns.
- UK: Year 12
- France: grade 12
- Iran: grade 12
- Afghanistan: grade 11
- Palestine: grade 11
Guide
To add or subtract two matrices, they must have the same order. Add the entries in the same places: the top left with the top left, and so on.
To multiply a matrix by a scalar (a number), multiply every entry by it, not just one.
To multiply two matrices, take a row of the first and a column of the second: multiply the entries in pairs and add them. The result goes in that row and that column. It is not an entry-by-entry product, and AB is usually not BA.
The transpose Aᵀ has the rows of A as its columns. A matrix of order 2×3 becomes 3×2. Ask your child to say the rule in their own words before they type.