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Chapter 8 Matrices and Determinants. By Richard Warner, Nate Huyser , Anastasia Sanderson, Bailey Grote. Chapter 8.1: General Matrices. Rectangular array of numbers called entries Dimensions of a matrix are number of rows by the number of columns. Chapter 8.1: Augmented Matrices.
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Chapter 8Matrices and Determinants By Richard Warner, Nate Huyser, Anastasia Sanderson, Bailey Grote
Chapter 8.1: General Matrices • Rectangular array of numbers called entries • Dimensions of a matrix are number of rows by the number of columns
Chapter 8.1: Augmented Matrices • Augmented Matrix- derived from a system of equations • Elementary Row Operations • Interchange any two rows • Multiply any row by a nonzero constant • Add two rows together • 2x2 by hand, 3x3 with calculator
Chapter 8.1: Reduced Row Echelon Form (RREF) • Any rows consisting of all zeros occur at the bottom of the matrix • All entries on the main diagonal are 1 • All entries not on the main diagonal or in the last column are 0 • A13 is the x-coordinate of the solution • A23 is the y-coordinate of the solution
Chapter 8.1: Gauss Jordan Elimination • Uses Augmented Matrices to solve systems of equations • Write system as an augmented matrix • Use the row operations to make A11 = 1 • Work down, around, and up to achieve RREF • Write last column as ordered pair for final answer
Chapter 8.1: Solving with Calculator (RREF) • Only used for Matrices larger than 2x2 • (2nd) [Matrix] → EDIT • Matrix[A] 3x4 • Enter entries by rows • (2nd) [Quit] • (2nd) [Matrix] → MATH • Select [RREF] • (2nd) [Matrix] select Martix[A]
Chapter 8.2: Matrix Operations Equality of Matrices: 2 matrices are equal if they have the same dimensions and their corresponding entries are equal To add and subtract Matrices: They must have the same dimensions. Add the corresponding entries Scalar Multiplication: Multiplying a matrix by a scalar (constant) Multiply each entry in the matrix by the scalar
Chapter 8.2: Matrix Operations Matrix Multiplication: • To Multiply AB, A’s columns must equal B’s rows • Multiply the entries in A’s rows by the corresponding entries in B’s columns • Amxn* Bnxr=ABmxr Ex: p.598 #29
Identity Matrices 8.3 Inverse Matrices I 2x2 I 3x3
Cont. 8.3 Inverse Multiplication • A A-1 =A-1 A =I • If A= where ad-bc cannot equal 0, Then A-1 =1/(ad-bc) * Inverse of2x2:
Cont. 8.3 Inverse Multiplication Inverse of 3x3 • Enter [matrix] in calculator • [matrix][A] [enter] [x-1 ] [enter] To solve a system of linear equations • Write the system of equations as a matrix problem • Find A-1 • X=A1B x =
8.4 Determinants • a real number derived from a square matrix • If A = then Det[A]= AD-CB • For 2x2 matrices only • For 3x3 matrices or larger • (2nd) Matrix → [Edit] A • Enter dimensions • (2nd) Quit • (2nd) Matrix → [Math] enter • (2nd) Matrix → enter
8.5 Determinant Applications • Cramer’s Rule solves systems using determinates. • Example:
8.5 Determinant Applications • Finding the area of a triangle where the points are (a,b), (c,d), (e,f) • Points are collinear if A=0