JEE Main 2019
Matrices & Determinants
Matrices and Determinants
Medium
Question
If \left| {\matrix{ {x - 4} & {2x} & {2x} \cr {2x} & {x - 4} & {2x} \cr {2x} & {2x} & {x - 4} \cr } } \right| = \left( {A + Bx} \right){\left( {x - A} \right)^2} then the ordered pair (A, B) is equal to :
Options
Solution
Key Concept: Properties of Determinants and Algebraic Comparison
This problem requires us to evaluate a determinant using elementary row and column operations. The goal is to simplify the determinant into a factored form and then compare it with a given algebraic expression to determine the values of constants and . The key properties of determinants we will use are:
- Column/Row Operations: Adding a multiple of one column (or row) to another column (or row) does not change the value of the determinant. This is useful for creating zeros or common factors.
- Factoring: A common factor from any single row or column can be taken out of the determinant.
- Triangular Determinant: The determinant of a triangular