1
NDA 2017 Paper 1
MCQ (Single Correct Answer)
+2.5
-0.83
The equations $$x + 2y + 3z = 1$$, $$2x + y + 3z = 2$$, $$5x + 5y + 9z = 4$$
A
have the unique solution
B
have infinitely many solutions
C
are inconsistent
D
None of the above
2
NDA 2017 Paper 1
MCQ (Single Correct Answer)
+2.5
-0.83
What is the value of the determinant

$$\left| {\matrix{ 1 & 1 & 1 \cr 1 & {1 + xyz} & 1 \cr 1 & 1 & {1 + xyz} \cr } } \right|$$ ?
A
1 + x + y + z
B
2 xyz
C
x2 y2 z2
D
2x2 y2 z2
3
NDA 2017 Paper 1
MCQ (Single Correct Answer)
+2.5
-0.83
If $$\left| {\matrix{ x & y & 0 \cr 0 & x & y \cr y & 0 & x \cr } } \right| = 0$$, then which one of the following is correct?
A
$${x \over y}$$ is one of the cube roots of unity
B
x is one of the cube roots of untiy
C
y is one of the cube roots of unity
D
$${x \over y}$$ is one of the cube roots of $$-$$ 1
4
NDA 2018 Paper 2
MCQ (Single Correct Answer)
+2.5
-0.83
For a square matrix A, which of the following properties hold?

1. $${({A^{ - 1}})^{ - 1}} = A$$

2. $$\det \,({A^{ - 1}}) = {1 \over {\det \,A}}$$

3. $${(\lambda A)^{ - 1}} = \lambda {A^{ - 1}}$$, where $$\lambda$$ is a scalar

Select the correct answer using the code given below.
A
1 and 2
B
2 and 3
C
1 and 3
D
1, 2 and 3
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