320 likes | 474 Vues
This guide provides essential information on determinants of square matrices, focusing on 2x2 and 3x3 matrices. The determinant for a 2x2 matrix is calculated as det.A = ad - bc, and for a 3x3 matrix, it involves a more complex formula: det.A = (aei + bfg + cdh) - (ceg + afh + bdi). Additionally, we explore Cramer’s Rule, which utilizes determinants to solve systems of linear equations, exemplified through specific equations. Practice problems are included to reinforce understanding.
E N D
Determinants Notation: det A |A| Can only be done for SQUARE matrices. (2x2, 3x3, etc.)
Determinant for 2x2 Matrix det A = ad - bc
Determinant for 2x2 Matrix det A = ad - bc
Determinant for 2x2 Matrix det A = ad - bc det C = 5(3) – 8(2)
Determinant for 2x2 Matrix det A = ad - bc det C = 5(3) – 8(2) = 15 – 16 = -1
Determinant for 3x3 Matrix det A = (aei + bfg + cdh)
Determinant for 3x3 Matrix det A = (aei + bfg + cdh) – (ceg + afh + bdi)
Determinant for 3x3 Matrix det A = (aei + bfg + cdh) – (ceg + afh + bdi) det B =
Determinant for 3x3 Matrix det A = (aei + bfg + cdh) – (ceg + afh + bdi) det B = (1*4*9 + 0*1*6 + 5*2*3)
Determinant for 3x3 Matrix det A = (aei + bfg + cdh) – (ceg + afh + bdi) det B = (1*4*9 + 0*1*6 + 5*2*3) – (6*4*5 + 3*1*1 + 9*2*0)
Determinant for 3x3 Matrix det A = (aei + bfg + cdh) – (ceg + afh + bdi) det B = (1*4*9 + 0*1*6 + 5*2*3) – (6*4*5 + 3*1*1 + 9*2*0) = (36 + 0 + 30) – (120 + 3 + 0)
Determinant for 3x3 Matrix det A = (aei + bfg + cdh) – (ceg + afh + bdi) det B = (1*4*9 + 0*1*6 + 5*2*3) – (6*4*5 + 3*1*1 + 9*2*0) = (36 + 0 + 30) – (120 + 3 + 0) = 66 – 123 = -57
Cramer’s Rule Uses matrices to solve systems of equations. ax + by = e cx + dy = f
Cramer’s Rule Uses matrices to solve systems of equations. ax + by = e cx + dy = f Coefficient Matrix
Cramer’s Rule Uses matrices to solve systems of equations. ax + by = e cx + dy = f Coefficient Matrix
Cramer’s Rule Uses matrices to solve systems of equations. ax + by = e cx + dy = f Coefficient Matrix
Cramer’s Rule Uses matrices to solve systems of equations. ax + by = e cx + dy = f Coefficient Matrix
Cramer’s Rule Uses matrices to solve systems of equations. ax + by = e cx + dy = f Coefficient Matrix
Cramer’s Rule 4x – 2y = -6 -3x + y = -3
Cramer’s Rule 4x – 2y = -6 -3x + y = -3 Coefficient Matrix
Cramer’s Rule 4x – 2y = -6 -3x + y = -3 Coefficient Matrix
Cramer’s Rule 4x – 2y = -6 -3x + y = -3 Coefficient Matrix
Cramer’s Rule 4x – 2y = -6 -3x + y = -3 Coefficient Matrix
Cramer’s Rule 4x – 2y = -6 -3x + y = -3 Coefficient Matrix
Cramer’s Rule 4x – 2y = -6 -3x + y = -3 Coefficient Matrix
Cramer’s Rule 4x – 2y = -6 -3x + y = -3 Coefficient Matrix
Cramer’s Rule 4x – 2y = -6 -3x + y = -3 Coefficient Matrix
Cramer’s Rule 4x – 2y = -6 -3x + y = -3 ( 6 , 15 ) Coefficient Matrix
Practice Find the determinate of the matrix.
Practice Use Cramer’s Rule to solve the system. (I’ve given the determinate to you already.) x – y = 2 2x + 3y = 14