260 likes | 472 Views
Determinants and Cramer’s Rule. Determinants. Determinants. A real number A ssociated with square (n x n) matrices Determinant for Matrix A is denoted as det A or | A |. Finding the Determinant of a 2 x 2 Matrix:. Example 1: Find the determinant. Example 2: Find the determinant.
E N D
Determinants • A real number • Associated with square (n x n) matrices • Determinant for Matrix A is denoted as det A or | A |
Cramer’s Rule • Method for solving linear systems using matrices -Can be used to solve a linear system of any size *We will only be working with linear systems in two variables
How to Solve Using Cramer’s Rule: • Create a coefficient matrix from the linear system ax + by = e cx + dy = f
How to Solve Using Cramer’s Rule: • Create a coefficient matrix from the linear system ax + by = e cx + dy = f *Note that the coefficients for x are the first column and the coefficients for y are the second column
How to Solve Using Cramer’s Rule: • Find the determinant of the coefficient matrix
How to Solve Using Cramer’s Rule: • Find the determinant of the coefficient matrix *If det A ≠ 0, then there is exactly one solution
How to Solve Using Cramer’s Rule: 3. Solve for x as follows: ax + by = e cx + dy = f
How to Solve Using Cramer’s Rule: 3. Solve for x as follows: ax + by = e cx + dy = f *Note the coefficients for x have been replaced with the constants from the linear system
How to Solve Using Cramer’s Rule: 4. Solve for y as follows: ax + by = e cx + dy = f
How to Solve Using Cramer’s Rule: 4. Solve for y as follows: ax + by = e cx + dy = f *Note the coefficients for y have been replaced with the constants from the linear system
How to Solve Using Cramer’s Rule: • Write the solution as a point (x,y)
How to Solve Using Cramer’s Rule: • Write the solution as a point (x,y) 6. Check your solution by substituting the values into the original equation
Example 1: Solve the following system using Cramer’s Rule: 2x + 7y = –3 3x – 8y = –23
Example 2: Solve the following system using Cramer’s Rule: 4x + 12y = 11 14x – 8y = 1
Practice 1: Solve the following system using Cramer’s Rule: 3x + 19y = 20 2x + 11y = 10
Homework: Page 607 #1 – 15