1
COMEDK 2020
MCQ (Single Correct Answer)
+1
-0

A vector perpendicular to the plane containing the points $$A(1, - 1,2),B(2,0, - 1),C(0,2,1)$$ is

A
$$8\widehat i + 4\widehat j + 4\widehat k$$
B
$$4\widehat i + 8\widehat j - 4\widehat k$$
C
$$\widehat i + \widehat j - \widehat k$$
D
$$3\widehat i + \widehat j + 2\widehat k$$
2
COMEDK 2020
MCQ (Single Correct Answer)
+1
-0

$${1 \over {2\,.\,5}} + {1 \over {5\,.\,8}} + {1 \over {8\,.\,11}} + ............. + {1 \over {(3n - 1)(3n + 2)}} = $$

A
$${n \over {6n + 3}}$$
B
$${n \over {6n - 4}}$$
C
$${{n + 1} \over {6n + 4}}$$
D
$${n \over {6n + 4}}$$
3
COMEDK 2020
MCQ (Single Correct Answer)
+1
-0

The ninth term of the expansion $${\left( {3x - {1 \over {2x}}} \right)^8}$$ is

A
$${{ - 1} \over {512{x^9}}}$$
B
$${1 \over {512{x^9}}}$$
C
$${1 \over {256.\,{x^8}}}$$
D
$${{ - 1} \over {256.\,{x^8}}}$$
4
COMEDK 2020
MCQ (Single Correct Answer)
+1
-0

If $$A = \left[ {\matrix{ 1 & { - 1} & 1 \cr 2 & 1 & { - 3} \cr 1 & 1 & 1 \cr } } \right],10B = \left[ {\matrix{ 4 & 2 & 2 \cr { - 5} & 0 & \alpha \cr 1 & { - 2} & 3 \cr } } \right]$$ and B is the inverse of A, then the value of $$\alpha$$ is

A
0
B
2
C
4
D
5
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