Question

Then the number of elements in the set {(n , m) : n ,m ∈ { 1, 2….., 10} and nA n + mB m = I} is _______.

Answer 1

The correct answer is : 1

A2 = A and B2 = BR

nA + mB = I,

So, 2 n – m = 1, – n + m = 0, 2 m – n = 1

So, (m , n) = (1, 1)