Home » Further Maths Unit 3 & 4 » OA1 - Matrices » 1.3 The Inverse of a Matrix

# 1.3 The Inverse of a Matrix

Contents

### The Determinant of a 2×2 Matrix

• The determinant of a 2 x 2 matrix can be calculated as:

\text { det }=A_{1,1} A_{2,2}-A_{1,2} A_{2,1}

• The determinant of an identity matrix is equal to 1.

Example

A=\left[\begin{array}{ll} 1 & 2 \\ 3 & 4 \end{array}\right]

The determinant of the above matrix is:

\operatorname{det}=1 * 4-2 * 3=-2

### Requirements for a Matrix to be Invertible

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