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If ∣111cb−xabac−x∣=0\begin{vmatrix}1 & 1 & 1\\ c & b-x & a\\ b & a & c-x\end{vmatrix}=0, then xx is equal to

Solution

✅ Correct Option: 2

Expanding along the first row, the determinant simplifies to x2+ab+bc+ca−a2−b2−c2x^2+ab+bc+ca-a^2-b^2-c^2. Setting it to zero gives x2=a2+b2+c2−ab−bc−ca=12[(a−b)2+(b−c)2+(c−a)2]x^2=a^2+b^2+c^2-ab-bc-ca=\dfrac12\left[(a-b)^2+(b-c)^2+(c-a)^2\right], so x=±12(a−b)2+(b−c)2+(c−a)2x=\pm\dfrac{1}{\sqrt2}\sqrt{(a-b)^2+(b-c)^2+(c-a)^2}.

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