JEE Main202225 Jul 2022Morning ShiftMathematicsMatricesActual
Let A = 2 - 1 - 1 1 0 - 1 1 - 1 0 and B = A - I . If ω = 3 i - 1 2 , then the number of elements in the set n ∈ 1 , 2 , … , 100 : A n + ω B n = A + B is equal to _____ .
Correct answer
0
Step-by-step solution
Given, A = 2 - 1 - 1 1 0 - 1 1 - 1 0 ⇒ A 2 = 2 - 1 - 1 1 0 - 1 1 - 1 0 2 - 1 - 1 1 0 - 1 1 - 1 0 = 2 - 1 - 1 1 0 - 1 1 - 1 0 = A ⇒ A n = A Now ∀ n ∈ 1 , 2 , … , 100 Now, B = A - I = 1 - 1 - 1 1 - 1 - 1 1 - 1 - 1 B 2 = 1 - 1 - 1 1 - 1 - 1 1 - 1 - 1 1 - 1 - 1 1 - 1 - 1 1 - 1 - 1 = - 1 - 1 - 1 1 - 1 - 1 1 - 1 - 1 = - B ⇒ B 3 = - B 2 = B ⇒ B 5 = B ⇒ B 99 = B Also, ω 3 k = 1 So, n = common of 1 , 3 , 5 , … , 99 and 3 , 6 , 9 , … , 99 = 17