Misc. 6 - Chapter 3 Class 12 Matrices

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Misc 6 Find the values of x, y, z if the matrix A = [■8(0&2𝑦&𝑧@𝑥&𝑦&−𝑧@𝑥&−𝑦&𝑧)] satisfy the equation A′A = I. Given, A = [■8(0&2𝑦&𝑧@𝑥&𝑦&−𝑧@𝑥&−𝑦&𝑧)] A’ = [■8(0&𝑥&𝑥@2𝑦&𝑦&−𝑦@𝑧&−𝑧&𝑧)] I = [■8(1&0&0@0&1&0@0&0&1)] Now, A’A = I Putting values [■8(0&𝑥&𝑥@2𝑦&𝑦&−𝑦@𝑧&−𝑧&𝑧)][■8(0&2𝑦&𝑧@𝑥&𝑦&−𝑧@𝑥&−𝑦&𝑧)] = [■8(1&0&0@0&1&0@0&0&1)] [■8(0(0)+𝑥(𝑥)+𝑥(𝑥)&0(2𝑦)+𝑥(𝑦)+𝑥(−𝑦)&0(𝑧)+𝑥(−𝑧)+𝑥(𝑧)@2𝑦(0)+𝑦(𝑥)−𝑦(𝑥)&2𝑦(2𝑦)+𝑦(𝑦)−𝑦(−𝑦)&2𝑦(𝑧)+𝑦(−𝑧)−𝑦(𝑧)@𝑧(0)−𝑧(𝑥)+𝑧(𝑥)&𝑧(2𝑦)−𝑧(𝑦)+𝑧(−𝑦)&𝑧(𝑧)−𝑧(−𝑧)+𝑧(𝑧))] = [■8(1&0&0@0&1&0@0&0&1)] [■8(0+𝑥^2+𝑥^2&0+𝑥𝑦−𝑥𝑦&0−𝑥𝑧+𝑥𝑧@0+𝑥𝑦−𝑥𝑦&4𝑦^2+𝑦^2+𝑦^2&2𝑧𝑦−𝑧𝑦−𝑧𝑦@0−𝑥𝑧+𝑥𝑧&2𝑧𝑦−𝑧𝑦−𝑧𝑦&𝑧^2+𝑧^2+𝑧^2 )]= [■8(1&0&0@0&1&0@0&0&1)] [■8(2𝑥^2&0&0@0&6𝑦^2&0@0&0&3𝑧^2 )]= [■8(1&0&0@0&1&0@0&0&1)] Since matrices are equal, corresponding elements are equal Thus, x = ± 1/√2 , y = ± 1/√6 , z = ± 1/√3 2x2 = 1 x2 = 1/2 x = ±√(1/2) x = ± 𝟏/√𝟐 6y2 = 1 y2 = 1/6 y = ±√(1/6) y = ± 𝟏/√𝟔 3z2 = 1 z2 = 1/3 z = ±√(1/3) z = ± 𝟏/√𝟑