If D = begin{vmatrix} a^2 + 1 & ab & ac ba & | vedclass

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(A) Given $D = \begin{vmatrix} a^2 + 1 & ab & ac \ ba & b^2 + 1 & bc \ ca & cb & c^2 + 1 \end{vmatrix}$.Multiply $R_1$ by $a$,$R_2$ by $b$,and $R_3$

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$1 + a^2 + b^2 + c^2$

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(A) Given $D = \begin{vmatrix} a^2 + 1 & ab & ac \ ba & b^2 + 1 & bc \ ca & cb & c^2 + 1 \end{vmatrix}$.Multiply $R_1$ by $a$,$R_2$ by $b$,and $R_3$ by $c$,and divide the determinant by $abc$:$D = \frac{1}{abc} \begin{vmatrix} a(a^2 + 1) & a^2b & a^2c \ ab^2 & b(b^2 + 1) & b^2c \ ac^2 & bc^2 & c(c^2 + 1) \end{vmatrix}$.Taking $a, b, c$ common from $C_1, C_2, C_3$ respectively:$D = \frac{abc}{abc} \begin{vmatrix} a^2 + 1 & a^2 & a^2 \ b^2 & b^2 + 1 & b^2 \ c^2 & c^2 & c^2 + 1 \end{vmatrix} = \begin{vmatrix} a^2 + 1 & a^2 & a^2 \ b^2 & b^2 + 1 & b^2 \ c^2 & c^2 & c^2 + 1 \end{vmatrix}$.Applying $C_1 ightarrow C_1 + C_2 + C_3$:$D = \begin{vmatrix} a^2 + b^2 + c^2 + 1 & a^2 & a^2 \ a^2 + b^2 + c^2 + 1 & b^2 + 1 & b^2 \ a^2 + b^2 + c^2 + 1 & c^2 & c^2 + 1 \end{vmatrix} = (1 + a^2 + b^2 + c^2) \begin{vmatrix} 1 & a^2 & a^2 \ 1 & b^2 + 1 & b^2 \ 1 & c^2 & c^2 + 1 \end{vmatrix}$.Applying $R_2 ightarrow R_2 - R_1$ and $R_3 ightarrow R_3 - R_1$:$D = (1 + a^2 + b^2 + c^2) \begin{vmatrix} 1 & a^2 & a^2 \ 0 & 1 & 0 \ 0 & 0 & 1 \end{vmatrix} = (1 + a^2 + b^2 + c^2)(1 - 0) = 1 + a^2 + b^2 + c^2$.

If $D = \begin{vmatrix} a^2 + 1 & ab & ac \\ ba & b^2 + 1 & bc \\ ca & cb & c^2 + 1 \end{vmatrix}$,then $D =$

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