Edexcel IGCSE Math B 5.C scalar multiplication of matrices

Practise scalar-matrix questions by multiplying each entry by the scalar, then adding or subtracting corresponding entries.

Exam points

Calculate expressions such as 3A-B or 3A-2B by working entry by entry.
Simplify matrix elements that contain variables such as m after scalar multiplication.

[Maximum number: 2]

$A=\begin{pmatrix}2&-3\\4&1\end{pmatrix}, \qquad B=\begin{pmatrix}5&0\\4&-2\end{pmatrix}.$
Calculate

2A-4B

Answer:
$\begin{pmatrix}-16&-6\\-8&10\end{pmatrix}.$

Marks: B2 fully correct; B1 for 2 or 3 correct elements in a $2\times2$ matrix.

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