JEE Main 2020
Matrices & Determinants
Matrices and Determinants
Medium
Question
Let A = {X = (x, y, z) T : PX = 0 and x 2 + y 2 + z 2 = 1} where P = \left[ {\matrix{ 1 & 2 & 1 \cr { - 2} & 3 & { - 4} \cr 1 & 9 & { - 1} \cr } } \right], then the set A :
Options
Solution
Key Concepts
This problem involves solving a system of homogeneous linear equations represented by a matrix equation , along with an additional constraint .
- Homogeneous System of Linear Equations: For a system where is an matrix, the nature of solutions depends on the determinant of :
- If , the system has only the trivial solution (i.e., ).
- If , the system has non-trivial solutions (inf