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Chapter 7. Systems and Matrices. 7.1. Solving Systems of Two Equations. Quick Review. Quick Review Solutions. What you’ll learn about. The Method of Substitution Solving Systems Graphically The Method of Elimination Applications … and why
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Chapter 7 Systems and Matrices
7.1 Solving Systems of Two Equations
What you’ll learn about • The Method of Substitution • Solving Systems Graphically • The Method of Elimination • Applications … and why Many applications in business and science can be modeled using systems of equations.
Solution of a System A solution of a system of two equations in two variables is an ordered pair of real numbers that is a solution of each equation.
7.2 Matrix Algebra
What you’ll learn about • Matrices • Matrix Addition and Subtraction • Matrix Multiplication • Identity and Inverse Matrices • Determinant of a Square Matrix • Applications … and why Matrix algebra provides a powerful technique to manipulate large data sets and solve the related problems that are modeled by the matrices.
Matrix Vocabulary Each element, or entry, aij, of the matrix uses double subscript notation. The row subscript is the first subscript i, and the column subscript is j. The element aij is the ith row and the jth column. In general, the orderof anm × n matrix is m×n.
Inverses of n× n Matrices An n× n matrix A has an inverse if and only if det A≠ 0.
Properties of Matrices Let A, B, and C be matrices whose orders are such that the following sums, differences, and products are defined. 1. Community property Addition: A + B = B + A Multiplication: Does not hold in general 2. Associative property Addition: (A + B) + C = A + (B + C) Multiplication: (AB)C = A(BC) 3. Identity property Addition: A + 0 = A Multiplication: A·In = In·A = A 4. Inverse property Addition: A + (-A) = 0 Multiplication: AA-1 = A-1A = In |A|≠0 5. Distributive property Multiplication over addition: A(B + C) = AB + AC (A + B)C = AC + BC Multiplication over subtraction: A(B - C) = AB - AC (A - B)C = AC - BC
7.3 Multivariate Linear Systems and Row Operations
What you’ll learn about • Triangular Forms for Linear Systems • Gaussian Elimination • Elementary Row Operations and Row Echelon Form • Reduced Row Echelon Form • Solving Systems with Inverse Matrices • Applications … and why Many applications in business and science are modeled by systems of linear equations in three or more variables.
Equivalent Systems of Linear Equations The following operations produce an equivalent system of linear equations. • Interchange any two equations of the system. • Multiply (or divide) one of the equations by any nonzero real number. • Add a multiple of one equation to any other equation in the system.
Row Echelon Form of a Matrix A matrix is in row echelon form if the following conditions are satisfied. • Rows consisting entirely of 0’s (if there are any) occur at the bottom of the matrix. • The first entry in any row with nonzero entries is 1. • The column subscript of the leading 1 entries increases as the row subscript increases.
Elementary Row Operations on a Matrix A combination of the following operations will transform a matrix to row echelon form. • Interchange any two rows. • Multiply all elements of a row by a nonzero real number. • Add a multiple of one row to any other row.