Determinant of 2x2 Matrix

Algebra Level 1

Given the 2 by 2 matrix $A = \begin{pmatrix} 5 & 1 \\ 1 & 5 \end{pmatrix} ,$ what is the value of $\det(A)$ ?

1 solution

Arron Kau Staff
May 13, 2014

For a $2 \times 2$ matrix $M = \begin{pmatrix} a & b \\ c & d \end{pmatrix}$ , the determinant is given by $\det(M) = ad - bc$ .

In our case, we have $\det(A) = 5(5) - 1(1) = 24$ .