If $\Delta = \begin{vmatrix} a & b & c \\ d & e & f \\ g & h & i \end{vmatrix} $ 

and A, B, C, D, G are the cofactors of the elements a, b, c, d, g respectively, then what is $bB+cC-dD-gG$ equal to?

. Consider the following statements in respect of the determinant 

$ \Delta = \begin{vmatrix} k(k+2) & 2k+1 & 1 \\ 2k+1 & k+2 & 1 \\ 3 & 3 & 1 \end{vmatrix} $

I. Δ is positive if $k>0$.

II. Δ is negative if $k<0$.

III. Δ is zero if $k=0$.

How many of the statements given above are correct?

If $ \begin{vmatrix} 2 & 3+i & -1 \\ 3-i & 0 & i -1 \\ -1 &-1 -i & 1 \end{vmatrix} = A + iB $

where i= $\sqrt{-1}$ ,  then what is A+B equal to?

If $A{}^2+B{}^2+C{}^2=0$, then what is the value of the following?

$\begin{vmatrix} 1& cosC& cosB\\ cosC&1&cosA \\ cosB&cosA&1 \end{vmatrix} $