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Explore the concepts of matrix inverses and identities with Jeffrey Bivin from Lake Zurich High School. Learn to find inverse matrices and the identity matrix for 2x2 matrices, along with solving systems using inverse matrices. Discover formulas and methods for determining if matrices are inverses of each other.
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Inverse & Identity MATRICES Jeffrey Bivin Lake Zurich High School jeff.bivin@lz95.org Last Updated: October 12, 2005
Inverses and Identities 5x = 3 Jeff Bivin -- LZHS
Now with Matrices ? This is the Identity Matrix for 2 x 2 Matrices Jeff Bivin -- LZHS
Let’s look at another example Jeff Bivin -- LZHS
New Question ? What do we multiply a matrix by to get the Identity? Jeff Bivin -- LZHS
INVERSE The Inverse of a 2x2 Matrix Jeff Bivin -- LZHS
INVERSE The Inverse of a 2x2 Matrix Jeff Bivin -- LZHS
INVERSE The Inverse of a 2x2 Matrix Jeff Bivin -- LZHS
A B This is our Formula! Jeff Bivin -- LZHS
A B This is our Formula! Jeff Bivin -- LZHS
A B C This is our Formula! Jeff Bivin -- LZHS
Are the two Matrices Inverses? The product of inverse matrices is the identity matrix. Identity, therefore, INVERSE Matrices Jeff Bivin -- LZHS
Are the two Matrices Inverses? The product of inverse matrices is the identity matrix. Not the Identity, therefore, NOT INVERSE Matrices Jeff Bivin -- LZHS
Does the Matrix have an Inverse? Let’s review the definition of the Inverse of a 2x2 Matrix Jeff Bivin -- LZHS
INVERSE The Inverse of a 2x2 Matrix Jeff Bivin -- LZHS
Does the Matrix have an Inverse? Find the determinant! Therefore,NOinverse! Jeff Bivin -- LZHS
Does the Matrix have an Inverse? Find the determinant! Therefore, an inverse exists! Jeff Bivin -- LZHS
Does the Matrix have an Inverse? + + Find the determinant! - - - 1•5•9 + 2•6•7 + 3•4•8 - 7•5•3 - 8•6•1 - 9•4•2 45 + 84 + 96 - 105 - 48 - 72 0 Therefore,NOinverse! Jeff Bivin -- LZHS
Does the Matrix have an Inverse? + + Find the determinant! - - - 1•4•2 + 3•1•3 + 2•2•4 - 3•4•2 - 4•1•1 - 2•2•3 8 + 9 + 16 - 24 - 4 - 12 -7 Therefore, an inverse exists! Jeff Bivin -- LZHS
Solve the system using inverse matrices A U B 3x + 2y = 7 4x - 5y = 11 This is our Formula! Jeff Bivin -- LZHS
Solve the system using inverse matrices A U B 2x - 4y = 9 3x - 2y = 1 This is our Formula! Jeff Bivin -- LZHS