1
JEE Main 2020 (Online) 9th January Morning Slot
+4
-1
Out of Syllabus
If the matrices A = $$\left[ {\matrix{ 1 & 1 & 2 \cr 1 & 3 & 4 \cr 1 & { - 1} & 3 \cr } } \right]$$,

B = adjA and C = 3A, then $${{\left| {adjB} \right|} \over {\left| C \right|}}$$ is equal to :
A
8
B
2
C
72
D
16
2
JEE Main 2020 (Online) 9th January Morning Slot
+4
-1
If for some $$\alpha$$ and $$\beta$$ in R, the intersection of the following three places
x + 4y – 2z = 1
x + 7y – 5z = b
x + 5y + $$\alpha$$z = 5
is a line in R3, then $$\alpha$$ + $$\beta$$ is equal to :
A
-10
B
0
C
10
D
2
3
JEE Main 2020 (Online) 8th January Evening Slot
+4
-1
The system of linear equations
$$\lambda$$x + 2y + 2z = 5
2$$\lambda$$x + 3y + 5z = 8
4x + $$\lambda$$y + 6z = 10 has
A
a unique solution when $$\lambda$$ = –8
B
no solution when $$\lambda$$ = 2
C
infinitely many solutions when $$\lambda$$ = 2
D
no solution when $$\lambda$$ = 8
4
JEE Main 2020 (Online) 8th January Evening Slot
+4
-1
If $$A = \left( {\matrix{ 2 & 2 \cr 9 & 4 \cr } } \right)$$ and $$I = \left( {\matrix{ 1 & 0 \cr 0 & 1 \cr } } \right)$$ then 10A–1 is equal to :
A
6I – A
B
4I – A
C
A – 6I
D
A – 4I
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