Table of contents
- 0. Review of Algebra4h 16m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 6m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 19m
- 10. Combinatorics & Probability1h 45m
7. Systems of Equations & Matrices
Determinants and Cramer's Rule
3:51 minutes
Problem 37d
Textbook Question
In Exercises 37 - 42, a. Write each linear system as a matrix equation in the form AX = B. b. Solve the system using the inverse that is given for the coefficient matrix. 2x + 6y + 6z = 8 2x + 7y + 6z = 10 2x + 7y + 7z = 9 The inverse of is
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1
Write the system of equations in matrix form: AX = B, where A is the coefficient matrix, X is the column matrix of variables, and B is the column matrix of constants.
Identify the coefficient matrix A as \( \begin{bmatrix} 2 & 6 & 6 \\ 2 & 7 & 6 \\ 2 & 7 & 7 \end{bmatrix} \), the variable matrix X as \( \begin{bmatrix} x \\ y \\ z \end{bmatrix} \), and the constant matrix B as \( \begin{bmatrix} 8 \\ 10 \\ 9 \end{bmatrix} \).
Express the matrix equation as \( \begin{bmatrix} 2 & 6 & 6 \\ 2 & 7 & 6 \\ 2 & 7 & 7 \end{bmatrix} \begin{bmatrix} x \\ y \\ z \end{bmatrix} = \begin{bmatrix} 8 \\ 10 \\ 9 \end{bmatrix} \).
Use the given inverse matrix \( \begin{bmatrix} \frac{7}{2} & 0 & -3 \\ -1 & 0 & 0 \\ 0 & -1 & 1 \end{bmatrix} \) to solve for X by multiplying both sides of the equation by the inverse of A.
Calculate \( X = A^{-1}B \) by performing the matrix multiplication \( \begin{bmatrix} \frac{7}{2} & 0 & -3 \\ -1 & 0 & 0 \\ 0 & -1 & 1 \end{bmatrix} \begin{bmatrix} 8 \\ 10 \\ 9 \end{bmatrix} \) to find the values of x, y, and z.
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