1
NDA Mathematics 4 September 2022
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
Let Δ be the determinant of a matrix A, where A = $\left[\begin{array}{lll}a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33} \end{array}\right]$ and C11, C12, C13 be the cofactors of a11, a12, a13 respectively.
What is the value of $a_{21}C_{11}+a_{22}C_{12}+a_{23}C_{13}$?
A
0
B
1
C
Δ
D
−Δ
2
NDA Mathematics 4 September 2022
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
Let Δ be the determinant of a matrix A, where A = $\left[\begin{array}{lll}a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33} \end{array}\right]$ and C11, C12, C13 be the cofactors of a11, a12, a13 respectively.

What is the value of $\left|\begin{array}{lll}\text{a}_{21} & \text{a}_{31} & \text{a}_{11} \\ \text{a}_{23} & \text{a}_{33} & \text{a}_{13} \\ \text{a}_{22} & \text{a}_{32} & \text{a}_{12}\end{array}\right|$ ?

A
0
B
1
C
Δ
D
−Δ
3
NDA Mathematics 4 September 2022
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
Let A = $\left(\begin{array}{ccc}0 & \sin^2 \theta & \cos^2 \theta \\ \cos^2 \theta & 0 & \sin^2 \theta \\ \sin^2 \theta & \cos^2 \theta & 0\end{array}\right)$ and A = P + Q where P is symmetric matrix and Q is skew-symmetric matrix.

What is the minimum value of determinant of A ?

A
$\frac{1}{4}$
B
$\frac{1}{2}$
C
$\frac{3}{4}$
D
1
4
NDA Mathematics 10 April 2022
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
If $Δ_1 = \begin{vmatrix} 1 & p & q \\ 1 & q & r \\ 1 & r & p\end{vmatrix} \ \text{and} \ Δ_2 = \begin{vmatrix} 1 & 1 & 1 \\ q & r & p \\ r & p & q \end{vmatrix}$ where p ≠ q ≠ r, then Δ1 + Δ2 is
A
0
B
always positive
C
always negative
D
positive if p, q, r are positive else negative
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