1
NDA 2018 Paper 2
MCQ (Single Correct Answer)
+2.5
-0.83
If a + b + c = 0, then one of the solutions of $$\left| {\matrix{ {a - x} & c & b \cr c & {b - x} & a \cr b & a & {c - x} \cr } } \right| = 0$$ is
A
x = a
B
$$x = \sqrt {{{3({a^2} + {b^2} + {c^2})} \over 2}} $$
C
$$x = \sqrt {{{2({a^2} + {b^2} + {c^2})} \over 3}} $$
D
x = 0
2
NDA 2018 Paper 2
MCQ (Single Correct Answer)
+2.5
-0.83
The system of equations

$$2x + y - 3z = 5$$

$$3x - 2y + 2z = 5$$

and $$5x - 3y - z = 16$$
A
is inconsistent
B
is consistent, with a unique solution
C
is consistent, with infinitely many solutions
D
has it solution lying along X-axis in three-dimensional space
3
NDA 2018 Paper 2
MCQ (Single Correct Answer)
+2.5
-0.83
If u, v and w (all positive) are the pth, qth, and rth terms of a GP, then the determinant of the matrix $$\left( {\matrix{ {\ln \,u} & p & 1 \cr {\ln v} & q & 1 \cr {\ln w} & r & 1 \cr } } \right)$$ is
A
0
B
1
C
(p $$-$$ q) (q $$-$$ r) (r $$-$$ p)
D
$${\ln \,u}$$ $$\times$$ $${\ln \,v}$$ $$\times$$ $${\ln \,w}$$
4
NDA 2018 Paper 2
MCQ (Single Correct Answer)
+2.5
-0.83
Let matrix B be the adjoint of a square matrix A, I be the identity matrix of same order as A. If k($$\ne$$ 0) is the determinant of the matrix A, then what is AB equal to?
A
I
B
kI
C
k2I
D
(1 / k)I
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