Mathematics
Grade 11
15 min
Add and subtract matrices
Add and subtract matrices
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1
Introduction & Learning Objectives
Learning Objectives
Define a matrix and identify its dimensions.
Determine if two matrices are compatible for addition or subtraction.
Accurately perform matrix addition on matrices of the same dimensions.
Accurately perform matrix subtraction on matrices of the same dimensions.
Solve for unknown variables or matrices in equations involving addition and subtraction.
By the end of of this lesson, students will be able to apply the commutative and associative properties of matrix addition.
Model and solve simple real-world problems using matrix addition and subtraction.
How does a video game track the inventory of multiple players at once? 🎮 It uses organized data structures, and the math behind them is simpler than you think!
This tutorial will introduce you to matrix add...
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Key Concepts & Vocabulary
TermDefinitionExample
MatrixA rectangular array of numbers, symbols, or expressions arranged in rows and columns. Matrices are typically denoted by a capital letter.A =
[ [1, -3], [5, 0] ]
Dimensions (or Order)The size of a matrix, described by its number of rows and columns. It is always written as 'rows × columns'.The matrix [ [2, 4, 1], [0, 7, 9] ] has 2 rows and 3 columns, so its dimensions are 2 × 3.
Element (or Entry)Each individual value within a matrix. An element's position is identified by its row and column number, often written as a_ij, where 'i' is the row and 'j' is the column.In the matrix [ [1, 2], [3, 4] ], the element a_21 is 3 (second row, first column).
Corresponding ElementsElements that are in the exact same position (the same row...
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Core Formulas
Condition for Addition and Subtraction
Matrices A and B can be added or subtracted only if they have the exact same dimensions (m × n).
This is the most important rule. If the dimensions do not match, the operation is undefined. You cannot add a 2 × 3 matrix to a 3 × 2 matrix.
Matrix Addition
If A = [a_ij] and B = [b_ij] are m × n matrices, then their sum A + B is the m × n matrix C = [c_ij] where c_ij = a_ij + b_ij.
To add two matrices, simply add their corresponding elements. The resulting matrix will have the same dimensions as the original matrices.
Matrix Subtraction
If A = [a_ij] and B = [b_ij] are m × n matrices, then their difference A - B is the m × n matrix D = [d_ij] where d_ij = a_ij - b_ij.
To subtract matrix B from matrix A, subtract each element of B f...
5 more steps in this tutorial
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Challenging
Find matrix X, given the following system of matrix equations: X + Y = [ [5, 8], [1, 6] ] and X - Y = [ [1, 2], [3, 0] ].
A.[ [3, 5], [2, 3] ]
B.[ [4, 6], [4, 6] ]
C.[ [2, 3], [-1, 3] ]
D.[ [6, 10], [4, 6] ]
Challenging
If A, B, and C are matrices of the same dimensions and A - B = C - B, what can be definitively concluded?
A.must be the zero matrix.
B.= C
C.= -C
D.A, B, and C must all be equal.
Challenging
A store's inventory is S = [ [15, 25], [20, 30] ] (Rows: Brand A, B; Cols: Laptops, Tablets). They sell W = [ [8, 18], [15, 20] ], receive a shipment R = [ [10, 15], [12, 10] ], and process returns C = [ [0, 2], [0, 0] ]. What is the final inventory matrix?
A.[ [17, 24], [17, 20] ]
B.[ [17, 20], [17, 20] ]
C.[ [17, 24], [17, 10] ]
D.[ [17, 22], [17, 20] ]
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