Chapter 6: Problem 57
If \(f(x)=\left|\begin{array}{ccc}x+c_{1} & x+a & x+a \\ x+b & x+c_{2} & x+a \\\ x+b & x+b & x+c_{3}\end{array}\right|\) and \(g(x)=\left(c_{1}-x\right)\) \(\left(c_{2}-x\right)\left(c_{3}-x\right)\), then \(f(0)\) is equal to (A) \(\frac{b g(a)-a g(b)}{(b-a)}\) (B) \(\frac{b g(a)+a g(b)}{(b+a)}\) (C) \(\frac{b g(a)-a g(b)}{(b+a)}\) (D) \(\frac{b g(a)+a g(b)}{(b-a)}\)
Short Answer
Step by step solution
Write the Determinant Expression
Expand the Determinant
Calculate Sub-Determinants
Substitute Back into f(x)
Evaluate f(0)
Use the Properties of Determinants
Compare with Options Using g(x)
Select the Correct Option
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Matrix Operations
To manage matrix operations efficiently:
- Understand the size or order of the matrix, for instance, 3x3 in our task.
- Know the elements' arrangement in rows and columns.
- Utilize matrix rules for operations, especially determinant calculations, crucial for this exercise.
Cofactor Expansion
Here's how to apply cofactor expansion:
- Select a row or column for the expansion. Generally, a row or column with the most zeros is preferred to simplify calculations.
- Calculate each cofactor, which is the signed minor of the selected element.
- Multiply each element by its corresponding cofactor and add them together to find the determinant.
Functions
Sub-Determinants
- Identify the 2x2 matrices by removing the respective row and column associated with the element of the main matrix undergoing cofactor expansion.
- Apply the formula: \( \text{det} \begin{vmatrix}a & b\ c & d\end{vmatrix} = ad - bc \) for the 2x2 matrix.
- Repeat this for each part specified by the cofactor expansion.