1
WB JEE 2018
MCQ (Single Correct Answer)
+2
-0.5
Change Language
From a collection of 20 consecutive natural numbers, four are selected such that they are not consecutive. The number of such selections is
A
284 $$ \times $$ 17
B
285 $$ \times $$ 17
C
284 $$ \times $$ 16
D
285 $$ \times $$ 16
2
WB JEE 2018
MCQ (Single Correct Answer)
+2
-0.5
Change Language
The least positive integer n such that $${\left( {\matrix{ {\cos \pi /4} & {\sin \pi /4} \cr { - \sin {\pi \over 4}} & {\cos {\pi \over 4}} \cr } } \right)^n}$$ is an identity matrix of order 2 is
A
4
B
8
C
12
D
16
3
WB JEE 2018
MCQ (Single Correct Answer)
+2
-0.5
Change Language
Let $$\rho $$ be a relation defined on N, the set of natural numbers, as

$$\rho $$ = {(x, y) $$ \in $$ N $$ \times $$ N : 2x + y = 41}. Then
A
$$\rho $$ is an equivalence relzation.
B
$$\rho $$ is only reflexive relation
C
$$\rho $$ is only symmetric relation
D
$$\rho $$ is not transitive
4
WB JEE 2018
MCQ (Single Correct Answer)
+2
-0.5
Change Language
If the polynomial $$f(x) = \left| {\matrix{ {{{(1 + x)}^a}} & {{{(2 + x)}^b}} & 1 \cr 1 & {{{(1 + x)}^a}} & {{{(2 + x)}^b}} \cr {{{(2 + x)}^b}} & 1 & {{{(1 + x)}^a}} \cr } } \right|$$, then the constant term of f(x) is
A
$$2 - {3.2^b} + {2^{3b}}$$
B
$$2 + {3.2^b} + {2^{3b}}$$
C
$$2 + {3.2^b} - {2^{3b}}$$
D
$$2 - {3.2^b} - {2^{3b}}$$
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