Mathematics
Grade 11
15 min
Solve a system of equations using augmented matrices
Solve a system of equations using augmented matrices
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Introduction & Learning Objectives
Learning Objectives
Convert a linear system of equations into its corresponding augmented matrix.
Identify and define the three elementary row operations.
Apply elementary row operations to transform a matrix into row echelon form.
Solve a system of two and three linear equations using Gaussian elimination with augmented matrices.
Interpret the final augmented matrix to determine if a system has one unique solution, no solution, or infinitely many solutions.
Use back-substitution to find the specific variable values from a matrix in row echelon form.
How could you solve a system with 10 equations and 10 variables without getting lost in a sea of substitutions? 🤯 Matrices provide a powerful and organized way to handle complex systems!
This tutorial will teach you how to rep...
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Key Concepts & Vocabulary
TermDefinitionExample
System of Linear EquationsA set of two or more linear equations that share the same variables.2x + 3y = 7
x - y = 1
MatrixA rectangular array of numbers arranged in rows and columns, enclosed in brackets.[ [1, 2, 3], [4, 5, 6] ] is a 2x3 matrix (2 rows, 3 columns).
Augmented MatrixA matrix that represents a system of linear equations. It consists of the coefficient matrix on the left and the constant terms on the right, separated by a vertical line.The system 2x + 3y = 7 and x - y = 1 becomes the augmented matrix [ [2, 3 | 7], [1, -1 | 1] ].
Row Echelon FormA form of a matrix where: 1) The first non-zero element in each row (the leading entry) is 1. 2) Each leading entry is in a column to the right of the leading entry of the row above it. 3) All rows consisting enti...
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Core Formulas
Row Operation 1: Row Swap
R_i \leftrightarrow R_j
Swap the position of any two rows. This is used to move a row with a desired leading entry to a higher position.
Row Operation 2: Scalar Multiplication
cR_i \rightarrow R_i
Multiply any row by a non-zero constant 'c'. This is used to create a leading entry of 1.
Row Operation 3: Row Addition/Subtraction
R_i + cR_j \rightarrow R_i
Add a multiple of one row to another row, replacing the original row. This is the primary tool for creating zeros below the leading entries.
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Challenging
Solve the system using an augmented matrix: x + y + z = 2, 2x - y + z = -1, x - 2y - z = 1.
A.x = 1, y = 1, z = 0
B.x = -1, y = 2, z = 1
C.x = 0, y = 1, z = 1
D.x = -1, y = 1, z = 2
Challenging
A student transforms matrix A = [ 1 -1 2 | 5 ]
[ 3 -5 1 | 7 ] into matrix B = [ 1 -1 2 | 5 ]
[ 0 -2 -5 | -8 ]. What single elementary row operation was performed?
A.R₂ + 3R₁ → R₂
B.R₂ - 3R₁ → R₂
C.R₁ - 3R₂ → R₁
D.3R₁ - R₂ → R₂
Challenging
A system is represented by [ 1 k | 4 ]
[ 3 -9 | h ]. Which condition on 'k' and 'h' guarantees the system has infinitely many solutions?
A.k = -3 and h = 12
B.k = 3 and h = 12
C.k = -3 and h ≠ 12
D.k = 3 and h ≠ 12
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