JEE Main 2024 Mathematics question
Let A = I − 2MM, where M is a real matrix of order 2 × 1 such that the relation MM = I holds. If λ is a real number such that the relation AX = λX holds for some non-zero real matrix X of order 2 × 1, then the sum of squares of all possible values of λ is equal to .
Answer: 2
Solution
A is a reflection (Householder) matrix with eigenvalues 1 and −1: 1 + 1 = 2.