Determinant 3 x 3 Matrix (Diagonal Method)

Determinant 3 x 3 Matrix (Diagonal Method)

Lesson 1

In diagonal method of solving determinants all the elements of the determinant are made zero, except the diagonal elements.

The elements are made zero by adding rows or columns; subtracting rows or columns; multiplying or dividing whole row or column by a scalar.

Problem: Calculate the determinant of each matrix.

Expand along the diagonal

Step 1: C1 C1- C2

Solution R3 R3 - R1

Step 2:

Solution C3 C3-C1

Step 3:

Solution The answer is: 6

Step 4:

Complete

Try two practice problems:

Calculate the determinant of each matrix.