Matrices and Determinants
Value of Determinant
JEE Main 2021
Grade 12
Question:
For the matrix $A = \begin{pmatrix} a & b \\ c & d \end{pmatrix}$, the determinant $|A|$ equals:
(1) $ad + bc$
(2) $ad - bc$
(3) $ac - bd$
(4) $ab - cd$
Step-by-Step Solution
Key Concept: This is simply the defining formula for the determinant of a $2 \times 2$ matrix — write down the rule for "product of the leading diagonal minus product of the other diagonal".
The detailed step-by-step mathematical proof is available inside the Mathbee app workspace.
Correct Answer: (2)