What is the value of \(\left| {\begin{array}{*{20}{c}} {{b^2} + {c^2}}&{ab}&{ac}\\ {ba}&{{c^2} + {a^2}}&{bc}\\ {ca}&{cb}&{{a^2} + {b^2}} \end{array}} \right|\)
What is the value of \(\left| {\begin{array}{*{20}{c}} {{b^2} + {c^2}}&{ab}&{ac}\\ {ba}&{{c^2} + {a^2}}&{bc}\\ {ca}&{cb}&{{a^2} + {b^2}} \end{array}} \right|\) Correct Answer 4a<sup>2</sup>b<sup>2</sup>c<sup>2</sup>
Calculation:
Expanding the determinant along Row 1.
= (b2 + c2) – (ab) + (ac)
= (b2 + c2) (a4 + a2b2 + a2c2 + c2b2 – b2c2) – ab (a3b + b3a – c2ab) + ac (ab2c – a3c – c3a)
= (b2 + c2) (a4 + a2b2 + a2c2) – a4b2 - a2b4 + a2b2c2 + a2b2c2 - a4c2 – a2c4
= 4a2b2c2
∴ Value of determinant is 4a2b2c2 .
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Feb 20, 2025