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4.7 Inverse Matrices and Systems. 1) Inverse Matrices and Systems of Equations. You have solved systems of equations using graphing, substitution , elimination …oh my… In the “real world”, these methods take too long and are almost never used. Inverse matrices are more practical.
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1) Inverse Matrices and Systems of Equations • You have solved systems of equations using graphing,substitution, elimination…oh my… • In the “real world”, these methods take too long and are almost never used. • Inverse matrices are more practical.
1) Inverse Matrices and Systems of Equations • For a • System of Equations
1) Inverse Matrices and Systems of Equations • For a We can write a • System of Equations Matrix Equation
1) Inverse Matrices and Systems of Equations • Example 1: • Write the system as a matrix equation
1) Inverse Matrices and Systems of Equations • Example 1: • Write the system as a matrix equation • Matrix Equation
1) Inverse Matrices and Systems of Equations • Example 1: • Write the system as a matrix equation • Matrix Equation Coefficient matrix Variable matrix Constant matrix
1) Inverse Matrices and Systems of Equations • Example 2:
1) Inverse Matrices and Systems of Equations • Example 2:
1) Inverse Matrices and Systems of Equations • Example 2: A X B
1) Inverse Matrices and Systems of Equations When rearranging, take the inverse of A
1) Inverse Matrices and Systems of Equations The Plan… “Solve the system” using matrices and inverses
1) Inverse Matrices and Systems of Equations • Example 3: • Solve the system
1) Inverse Matrices and Systems of Equations • Example 3: • Solve the system • Step 1: Write a matrix equation
1) Inverse Matrices and Systems of Equations • Example 3: • Solve the system • Step 1: Write a matrix equation
1) Inverse Matrices and Systems of Equations • Example 3: • Solve the system • Step 2: Find the determinant and A-1
1) Inverse Matrices and Systems of Equations • Example 3: • Solve the system • Step 2: Find the determinant and A-1 Change signs Change places
1) Inverse Matrices and Systems of Equations • Example 3: • Solve the system • Step 2: Find the determinant and A-1 Change signs Change places detA = 4 – 3 = 1
1) Inverse Matrices and Systems of Equations • Example 3: • Solve the system • Step 2: Find the determinant and A-1
1) Inverse Matrices and Systems of Equations • Example 3: • Solve the system • Step 3: Solve for the variable matrix
1) Inverse Matrices and Systems of Equations • Example 3: • Solve the system • Step 3: Solve for the variable matrix
1) Inverse Matrices and Systems of Equations • Example 3: • Solve the system • Step 3: Solve for the variable matrix
1) Inverse Matrices and Systems of Equations • Example 3: • Solve the system • Step 3: Solve for the variable matrix The solution to the system is (4, 1).
1) Inverse Matrices and Systems of Equations • Example 4: • Solve the system. Check your answer.
1) Inverse Matrices and Systems of Equations • Example 4: • Solve the system. Check your answer.
1) Inverse Matrices and Systems of Equations • Example 4: • Solve the system. Check your answer. detA = 10 - 9 = 1
1) Inverse Matrices and Systems of Equations • Example 4: • Solve the system. Check your answer.
1) Inverse Matrices and Systems of Equations • Example 4: • Solve the system. Check your answer. The solution to the system is (-1, 4).
1) Inverse Matrices and Systems of Equations • Example 4: • Solve the system. Check your answer. • Check
1) Inverse Matrices and Systems of Equations • What about a matrix that has no inverse? • It will have no unique solution.
1) Inverse Matrices and Systems of Equations • Example 5: • Determine whether the system has a unique solution.
1) Inverse Matrices and Systems of Equations • Example 5: • Determine whether the system has a unique solution. • Find the determinant.
1) Inverse Matrices and Systems of Equations • Example 5: • Determine whether the system has a unique solution. • Find the determinant.
1) Inverse Matrices and Systems of Equations • Example 5: • Determine whether the system has a unique solution. • Find the determinant. Since detA = 0, there is no inverse. The system does not have a unique solution.
Homework • p.217 #1-5, 7-10, 20, 21, 23, 24, 26, 27, 36 • DUE TOMORROW: Two codes • TEST: Wednesday Nov 25 • Chapter 4