JEE Main 2024 Mathematics question
If the system of equations x + 4y − z = λ, 7x + 9y + μz = −3, 5x + y + 2z = −1 has infinitely many solutions, then (2μ + 3λ) is equal to:
Answer: (B)
Solution
The coefficient determinant is zero for μ = 0, and the consistency condition then gives λ = −1, so 2μ + 3λ = −3.