Chapter 3: Problem 2
Use determinants to find which real values of \(c\) make each of the following matrices invertible. a. \(\left[\begin{array}{rrr}1 & 0 & 3 \\ 3 & -4 & c \\ 2 & 5 & 8\end{array}\right]\) b. \(\left[\begin{array}{rrr}0 & c & -c \\ -1 & 2 & 1 \\ c & -c & c\end{array}\right]\) c. \(\left[\begin{array}{rrr}c & 1 & 0 \\ 0 & 2 & c \\ -1 & c & 5\end{array}\right]\) d. \(\left[\begin{array}{lll}4 & c & 3 \\ c & 2 & c \\ 5 & c & 4\end{array}\right]\) e. \(\left[\begin{array}{rrr}1 & 2 & -1 \\ 0 & -1 & c \\ 2 & c & 1\end{array}\right]\) f. \(\left[\begin{array}{rrr}1 & c & -1 \\ c & 1 & 1 \\ 0 & 1 & c\end{array}\right]\)
Short Answer
Step by step solution
Understand Matrix Invertibility Using Determinants
Step 2a: Calculate Determinant for Matrix (a)
Step 2b: Calculate Determinant for Matrix (b)
Step 2c: Calculate Determinant for Matrix (c)
Step 2d: Calculate Determinant for Matrix (d)
Step 2e: Calculate Determinant for Matrix (e)
Step 2f: Calculate Determinant for Matrix (f)
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Determinants
Real Values of c
- For Matrix (a): The determinant is calculated as \(19 - 5c\). To ensure invertibility, set \(19 - 5c eq 0\) yielding \(c eq \frac{19}{5}\).
- For Matrix (b): The determinant is \(5c^2\). Thus, \(c eq 0\) since any non-zero value ensures invertibility.
- For Matrix (c): The determinant becomes \(10c\). Hence, \(c eq 0\) for invertibility.