Calculate 3 * [[1,-2],[0,4]]: animated lesson

1. 1. The problem
   Worked example

   k × A: A = [[1, -2], [0, 4]]
2. 2. Step by step
   1. $$A = \begin{bmatrix}1 & -2 \\ 0 & 4\end{bmatrix}\ (2×2)$$
      Read matrix A
   2. $$3A = \begin{bmatrix}3 & -6 \\ 0 & 12\end{bmatrix}$$
      Multiply every entry by k = 3
   3. $$\begin{bmatrix}3 & -6 \\ 0 & 12\end{bmatrix}$$
      Result
3. 3. The answer
   $$\begin{bmatrix}3 & -6 \\ 0 & 12\end{bmatrix}$$

   [[3, -6], [0, 12]]

4. 4. Check
   • ✓All arithmetic is exact (fractions, no rounding).

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