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MTH 204 — Linear Algebra I: Lecture Note

Mathematics · 200 Level

About this lecture note

This is the complete lecture note for MTH 204 Linear Algebra I, prepared for Mathematics students at 200 Level. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.

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LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Series 1: Systems of Linear Equations and Matrices Series outline Part 1.1: Introduction to Systems of Linear Equations Definition of a system of linear equations Consistent and inconsistent systems Homogeneous and non-homogeneous systems Part 1.2: Methods of Solving Linear Systems Graphical method Substitution and elimination methods Matrix method (overview) Part 1.3: Matrices and Basic Operations Definition of a matrix Types of matrices (row, column, square, zero, identity) Matrix addition, subtraction, and scalar multiplication Part 1.4: Matrix Multiplication and Properties Rules of matrix multiplication Properties of matrix multiplication Applications in solving systems of equations Part 1.5: Elementary Row Operations and Row Echelon Form Elementary row operations Row echelon form and reduced row echelon form Solving systems using Gaussian elimination Introduction Linear algebra provides the language and tools for solving problems that arise in science, engineering, economics, and many other fields. At the heart of this subject lies the study of systems of linear equations and matrices, which form the foundation for more advanced concepts such as determinants, vector spaces, and transformations. Understanding how to represent and solve systems of equations is therefore essential, as it equips learners with methods that are both practical and theoretical, and prepares them for the deeper explorations that follow in this course.

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS The aim of this Series is to introduce you to systems of linear equations and matrices, and to equip you with the skills needed to represent, manipulate, and solve these systems using a variety of methods. We shall commence this Series by examining the nature of systems of linear equations, including consistent and inconsistent systems as well as homogeneous and non-homogeneous cases. Next, we will explore methods of solving such systems, beginning with graphical approaches and progressing to substitution, elimination, and matrix methods. Following that, we will study matrices in detail, considering their types and basic operations such as addition, subtraction, and scalar multiplication. We will then move on to matrix multiplication and its properties, highlighting its role in solving systems of equations. Finally, we will wrap up by introducing elementary row operations and row echelon forms, and demonstrate how Gaussian elimination can be applied to find solutions efficiently. Series Learning Outcomes Upon completing this Series, you should be able to: SLO 1.1 define a system of linear equations and distinguish between consistent, inconsistent, homogeneous, and non-homogeneous systems, SLO 1.2 demonstrate methods of solving systems of linear equations using graphical, substitution, and elimination approaches, SLO 1.3 describe the concept of a matrix and classify different types of matrices such as row, column, square, zero, and identity, SLO 1.4 apply matrix operations including addition, subtraction, scalar multiplication, and matrix multiplication to solve problems, SLO 1.5 perform elementary row operations to transform matrices into row echelon and reduced row echelon forms, and SLO 1.6 solve systems of linear equations using Gaussian elimination. 1.1 Introduction To Systems Of Linear Equations 1.1.1 Definition of a system of linear equations A system of linear equations is a collection of two or more linear equations involving the same set of variables. Each equation represents a straight line or plane, and the solution to the system is the set of values that satisfies all equations simultaneously. For example, the system: 2x+y=5,x-y=1 represents two lines in the plane. The point where they intersect gives the solution. Fill in the blank: A system of linear equations is a collection of __________ equations involving the same variables. Graphical representation of a system of two linear equations. ” 1.1.2 Consistent and inconsistent systems

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS A system is consistent if it has at least one solution, and inconsistent if it has no solution. Consistent systems may have a unique solution or infinitely many solutions. Inconsistent systems occur when equations represent parallel lines that never meet. Fill in the blank: A system with no solution is called __________.

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Parallel lines representing an inconsistent system of equations. 1.1.3 Homogeneous and non-homogeneous systems A homogeneous system is one in which all constant terms are zero, for example: x+y=0,2x-y=0 Such systems always have at least one solution, the trivial solution where all variables equal zero. A non-homogeneous system has at least one non-zero constant term, for example: x+y=3,2x-y=1 Fill in the blank: A system where all constant terms are zero is called __________. [Insert box here] Caption: Box 1.1: Homogeneous vs non-homogeneous systems Homogeneous: All constants are zero, always has trivial solution. Non-homogeneous: At least one constant is non-zero, may have unique or no solution.

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Pilot questions 1.1 A system of linear equations is: A. A collection of linear equations involving the same variables B. A single equation only C. Random guess D. Arbitrary A system with at least one solution is called: A. Consistent B. Inconsistent C. Random guess D. Arbitrary A system with no solution is called: A. Inconsistent B. Consistent C. Random guess D. Arbitrary A homogeneous system has: A. All constant terms equal to zero B. At least one constant term non-zero C. Random guess D. Arbitrary The trivial solution of a homogeneous system is: A. All variables equal to zero B. All variables equal to one C. Random guess D. Arbitrary 1.2 Methods Of Solving Linear Systems 1.2.1 Graphical method The graphical method involves plotting each equation of a system on a coordinate plane and identifying the point(s) where the graphs intersect. Each intersection represents a solution to the system. If the lines intersect at a single point, the system has a unique solution. If the lines overlap completely, the system has infinitely many solutions. If the lines are parallel, the system has no solution.

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Fill in the blank: When two lines intersect at a single point, the system has a __________ solution. Graphical solutions of linear systems. 1.2.2 Substitution method The substitution method involves solving one equation for one variable and substituting this expression into the other equation. This reduces the system to a single equation with one variable, which can then be solved. Example: Solve the system: x+y=6,x-y=2 From the first equation: x=6-y. Substituting into the second: (6-y)-y=2⇒6-2y=2⇒y=2,x=4

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Fill in the blank: In the substitution method, one equation is solved for one __________ and substituted into the other. : Steps in substitution method Solve one equation for one variable. Substitute into the other equation. Solve for the remaining variable. Back-substitute to find the first variable. 1.2.3 Elimination method

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