JEE Main 2020
Matrices & Determinants
Matrices and Determinants
Medium
Question
Let be a root of the equation x 2 + x + 1 = 0 and the matrix A = {1 \over {\sqrt 3 }}\left[ {\matrix{ 1 & 1 & 1 \cr 1 & \alpha & {{\alpha ^2}} \cr 1 & {{\alpha ^2}} & {{\alpha ^4}} \cr } } \right] then the matrix A 31 is equal to
Options
Solution
Key Concepts and Formulas
This problem primarily relies on the properties of the cube roots of unity and standard matrix multiplication.
- Cube Roots of Unity: The roots of the equation are . The equation is derived from factoring , so its roots are and . Key properties include:
- From , it