JEE Main 2019
Matrices & Determinants
Matrices and Determinants
Medium
Question
If + + = 2, then the system of equations x + (cos )y + (cos )z = 0 (cos )x + y + (cos )z = 0 (cos )x + (cos )y + z = 0 has :
Options
Solution
Key Concept: Nature of Solutions for Homogeneous Linear Systems
A system of linear equations is called homogeneous if all the constant terms are zero. Such a system can be written in matrix form as , where is the coefficient matrix, is the column vector of variables, and is the zero column vector.
For a homogeneous system :
- If the determinant of the coefficient matrix, , is non-zero (), the system has only the trivial solution (). This is a unique solution.
- If the determinant of the coefficient matrix,