Matrix Addition and Multiplication
Aligned to N-VM.C.8 — Common Core State Standards for Mathematics.
What this lesson teaches
This is a (+) advanced standard. Add or subtract matrices of the same size entry by entry. Multiply two matrices when the first matrix's number of columns equals the second's number of rows; each entry is a row-times-column dot product.
Worked example
Multiply [[1, 2], [3, 4]] × [[5, 6], [7, 8]]. Top-left = 1×5 + 2×7 = 19, top-right = 1×6 + 2×8 = 22, bottom-left = 3×5 + 4×7 = 43, bottom-right = 3×6 + 4×8 = 50, giving [[19, 22], [43, 50]].
Practice questions
- Add [[1, 0], [2, 3]] + [[4, 5], [1, 1]].
- Can you multiply a 2×3 matrix by a 2×2 matrix? Explain.
- Multiply [[2, 0], [1, 3]] × [[1, 4], [2, 1]].
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Suma y multiplicación de matrices
Este es un estándar avanzado (+). Suma o resta matrices del mismo tamaño entrada por entrada. Multiplica dos matrices cuando el número de columnas de la primera es igual al número de filas de la segunda; cada entrada es un producto punto de fila por columna.
Ejemplo: Multiplica [[1, 2], [3, 4]] × [[5, 6], [7, 8]]. Arriba-izquierda = 1×5 + 2×7 = 19, arriba-derecha = 1×6 + 2×8 = 22, abajo-izquierda = 3×5 + 4×7 = 43, abajo-derecha = 3×6 + 4×8 = 50, lo que da [[19, 22], [43, 50]].
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