Mathematics Grade 10 15 min

Add and subtract scalar multiples of matrices

Add and subtract scalar multiples of matrices

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1

Introduction & Learning Objectives

Learning Objectives Define a scalar and identify the dimensions of a matrix. Perform scalar multiplication on a matrix of any dimension. Determine if two matrices can be added or subtracted based on their dimensions. Accurately add or subtract two matrices with the same dimensions. Evaluate expressions that combine scalar multiplication with matrix addition and subtraction. Solve simple matrix equations involving these operations. Imagine you're managing inventory for two stores and suddenly, you need to double the stock at one store and combine the totals. How could you organize that information efficiently? 📦 This tutorial introduces matrices as a powerful tool for organizing data. You will learn how to scale data sets using scalar multiplication and how to combine...
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Key Concepts & Vocabulary

TermDefinitionExample MatrixA rectangular arrangement of numbers, symbols, or expressions in rows and columns. It is enclosed in brackets.A = [ [1, 2], [3, 4] ] is a 2x2 matrix (2 rows, 2 columns). DimensionsThe size of a matrix, described by its number of rows and columns, written as 'rows x columns'.The matrix [ [5, 0, -2], [7, 1, 9] ] has dimensions 2x3. Element (or Entry)Each individual value within a matrix.In the matrix [ [1, 2], [3, 4] ], the number 3 is an element. ScalarAn ordinary number (a real number) that is used to multiply a matrix.In the expression 5B, the number 5 is the scalar. Scalar MultiplicationThe operation of multiplying a matrix by a scalar. Every element in the matrix is multiplied by the scalar.If k = 3 and A = [ [1, 2], [3, 4] ], then kA = [ [3*1, 3*2...
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Core Formulas

Scalar Multiplication k * A = k * [a_ij] = [k * a_ij] To multiply a matrix A by a scalar k, you must multiply every single element (a_ij) inside the matrix by k. The dimensions of the resulting matrix are the same as the original matrix. Matrix Addition A + B = [a_ij] + [b_ij] = [a_ij + b_ij] To add two matrices, they MUST have the exact same dimensions. You add the corresponding elements from each matrix to get the new matrix. Matrix Subtraction A - B = [a_ij] - [b_ij] = [a_ij - b_ij] To subtract two matrices, they MUST have the exact same dimensions. You subtract the corresponding elements of the second matrix from the first matrix.

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Sample Practice Questions

Challenging
Let A = [ [-2, k], [1, 0] ] and B = [ [6, -8], [-5, 4] ]. Find the value of the scalar k such that the element in the first row, second column of the matrix 4A + B is equal to 0.
A.k = 1
B.k = -2
C.k = -4
D.k = 2
Challenging
Solve for the 2x2 matrix X in the equation: 3X + [ [1, -2], [0, 4] ] = 2X + [ [0, 3], [5, -1] ].
A.[ [-1, 5], [5, -5] ]
B.[ [1, 1], [5, 3] ]
C.[ [1, -5], [-5, 5] ]
D.[ [-1, 1], [5, -3] ]
Challenging
Let A = [ [1, 2], [3, 4] ] and B = [ [-1, 0], [2, 1] ]. Find a 2x2 matrix C such that 2A + C = 3B.
A.[ [-1, -4], [-4, -5] ]
B.[ [1, 4], [4, 5] ]
C.[ [-5, -4], [0, -5] ]
D.[ [5, 4], [0, 5] ]

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