Let ∆ = 0 and ∆ c denotes the determinant of cofactors, then ∆ c = ∆ n – 1 , where n (>…

Mathematics · JEE Advanced · NTA ExamsMatrices and Determinants


Let ∆ = 0 and ∆c denotes the determinant of cofactors, then ∆c = ∆n – 1, where n (> 0) is the order of ∆.
On the basis of above information, answer the following questions :
If l1, m1, n1 ; l2, m2, n2 ; l3, m3, n3 are real quantities satisfying the six relations :
\(\ell_{1}^{2}+\mathrm{m}_{1}^{2}+\mathrm{n}_{1}^{2}\)= \(\ell_{2}^{2}+\mathrm{m}_{2}^{2}+\mathrm{n}_{2}^{2}\)=\(\ell_{3}^{2}+\mathrm{m}_{3}^{2}+\mathrm{n}_{3}^{2}\)= 1
l2 l3 + m2 m3 + n2 n3 = l3 l1 + m3 m1 + n3 n1 =
l1 l2 + m1 m2 + n1 n2 = 0, then the value of
\[\left|\begin{array}{lll} \ell_{1} & \mathrm{~m}_{1} & \mathrm{n}_{1} \\ \ell_{2} & \mathrm{~m}_{2} & \mathrm{n}_{2} \\ \ell_{3} & \mathrm{~m}_{3} & \mathrm{n}_{3} \end{array}\right|\] is
  1. 0
  2. ± 1
  3. ± 2
  4. ± 3

Answer

(B) ± 1

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