Question
Download Solution PDFThe value of \(\left|\begin{array}{ccc} -a^{2} & a b & a c \\ a b & -b^{2} & b c \\ a c & b c & -c^{2} \end{array}\right| \) is :
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept Used:
Properties of determinants.
Factor out common terms from rows or columns.
Calculation:
Given:
Δ = \(\begin{vmatrix} -a^2 & ab & ac \\ ab & -b^2 & bc \\ ac & bc & -c^2 \end{vmatrix}\)
Taking a, b, c common from R₁, R₂, and R₃, respectively, we get
Δ = abc \(\begin{vmatrix} -a & b & c \\ a & -b & c \\ a & b & -c \end{vmatrix}\) = a²b²c² \(\begin{vmatrix} -1 & 1 & 1 \\ 1 & -1 & 1 \\ 1 & 1 & -1 \end{vmatrix}\)
[taking a, b, c common from C₁, C₂, C₃ respectively]
Δ = a²b²c² \(\begin{vmatrix} -1 & 0 & 0 \\ 1 & 0 & 2 \\ 1 & 2 & 0 \end{vmatrix}\) (applying C₂ → C₂ + C₁, C₃ → C₃ + C₁)
Δ = a²b²c² (-1) \(\begin{vmatrix} 0 & 2 \\ 2 & 0 \end{vmatrix}\) = a²b²c² (-1) (0 - 4)
Δ = 4a²b²c²
Hence option 3 is correct
Last updated on Jul 3, 2025
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