1
WB JEE 2019
MCQ (Single Correct Answer)
+1
-0.25
Change Language
There are 7 greeting cards, each of a different colour and 7 envelopes of same 7 colours as that of the cards. The number of ways in which the cards can be put in envelopes, so that exactly 4 of the cards go into envelopes of respective colour is,
A
$${}^7{C_3}$$
B
2 . $${}^7{C_3}$$
C
3! $${}^4{C_4}$$
D
3! $${}^7{C_3}$$$${}^4{C_3}$$
2
WB JEE 2019
MCQ (Single Correct Answer)
+1
-0.25
Change Language
72n + 16n $$-$$1 (n$$ \in $$ N) is divisible by
A
65
B
63
C
61
D
64
3
WB JEE 2019
MCQ (Single Correct Answer)
+1
-0.25
Change Language
The number of irrational terms in the expansion of $${\left( {{3^{{1 \over 8}}} + {5^{{1 \over 4}}}} \right)^{84}}$$ is
A
73
B
74
C
75
D
76
4
WB JEE 2019
MCQ (Single Correct Answer)
+1
-0.25
Change Language
Let A be a square matrix of order 3 whose all entries are 1 and let I3 be the identity matrix of order 3. Then, the matrix $$A - 3{I_3}$$ is
A
invertible
B
orthogonal
C
non-invertible
D
real Skew Symmetric matrix
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