1
NDA Mathematics 13 April 2025
MCQ (Single Correct Answer)
+2.5
-0.833
Change Language

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 equal to?

A
0
B
1
C
Δ
D
Δ
2
NDA Mathematics 13 April 2025
MCQ (Single Correct Answer)
+2.5
-0.833
Change Language

. 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 .

II. Δ is negative if .

III. Δ is zero if .

How many of the statements given above are correct?

A
None 
B
One 
C
Two 
D
All three
3
NDA Mathematics 13 April 2025
MCQ (Single Correct Answer)
+2.5
-0.833
Change Language

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?

A
-10
B
-6
C
0
D
6
4
NDA Mathematics 13 April 2025
MCQ (Single Correct Answer)
+2.5
-0.833
Change Language

If , then what is the value of the following?

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

A
-1
B
0
C
1
D
2
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