Mastering Inverse Matrices for Linear Systems
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Learn to find inverse of square matrices, solve matrix equations using inverses, and tackle linear systems efficiently with inverse matrices. Practice exercises included.
Mastering Inverse Matrices for Linear Systems
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Presentation Transcript
Use Inverse Matrices to Solve Linear Systems Objectives • To find the inverse of a square matrix • To solve a matrix equation using inverses • To solve a linear system using inverse matrices
Warm-Up Imagine you lived in a world that never defined subtraction or division. What would you do to get the same results?
Objective 1 You will be able to find the inverse of a square matrix
Identity Matrix The identity matrix has 1s along the main diagonal and zeros everywhere else.
Identity Matrix Recall that multiplying a number by 1 gives you back the same number. This is the Identity Property of Multiplication. Similarly, multiplying a matrix by the identity matrix, , will return the original matrix.
Exercise 1 Find : and
Inverse Matrix The inverseof a square matrix is another square matrix such that and . The inverse of matrix is denoted as The inverse is only defined for a square matrix with a determinant
Exercise 2 Find . What is the relationship between , , and ? and
Exercise 3 Find :
Exercise 4 Find :
Objective 2 You will be able to solve a matrix equation using inverses
Matrix Equations In general a matrix equation can be written as , where , , and are matrices. To solve this equation for , you would ordinarily divide by . However, there is no matrix division. Instead you solve for by multiplying both sides of the equation by the inverse of .
Matrix Equations In general a matrix equation can be written as , where , , and are matrices. How to solve a matrix equation Since matrix multiplication is not commutative, you must remember to always multiply on the same side.
Exercise 5 Solve the matrix equation for .
Exercise 6 Solve the matrix equation for .
Objective 3 You will be able to solve a linear system using inverse matrices
Exercise 7 Use an inverse matrix to solve the linear system.
Solving Systems using Inverses Write the system as a matrix equation Find the inverse of matrix Multiply both left sides of by Step 1 Step 2 Step 3 is the coefficient matrix The solution is is the constant matrix
Protip: Multiplying by Inverse When multiplying by an inverse matrix to solve a matrix equation, first multiply by the “sub-inverse” and then divide each element by the determinant. “Sub-inverse” 1 divided by the determinant
Exercise 8 Solve each system using inverse matrices.
Inverse Matrix (3x3) The inverse of a matrix is
Inverse Matrix (3x3) The inverse of a matrix is just use a calculator!
Exercise 9 Find .
Exercise 10 Find .
Exercise 11 Solve the system using inverse matrices.
Exercise 12 Solve the system using inverse matrices.
3.8: Use Inverse Matrices to Solve Linear Systems Objectives • To find the inverse of a square matrix • To solve a matrix equation using inverses • To solve a linear system using inverse matrices