1
WB JEE 2008
MCQ (Single Correct Answer)
+1
-0.25

If $${}^{16}{C_r} = {}^{16}{C_{r + 1}}$$, then the value of $${}^r{P_{r - 3}}$$ is

A
31
B
120
C
210
D
840
2
WB JEE 2008
MCQ (Single Correct Answer)
+1
-0.25

The coefficient of x$$-$$10 in $${\left( {{x^2} - {1 \over {{x^3}}}} \right)^{10}}$$ is

A
$$-$$ 252
B
$$-$$ 210
C
$$-$$ (5!)
D
$$-$$ 120
3
WB JEE 2009
MCQ (Single Correct Answer)
+1
-0.25

Product of any r consecutive natural numbers is always divisible by

A
r!
B
(r + 4)!
C
(r + 1)!
D
(r + 2)!
4
WB JEE 2009
MCQ (Single Correct Answer)
+1
-0.25

For each n $$\in$$ N, 23n $$-$$ 1 is divisible by

here N is a set of natural numbers.

A
7
B
8
C
6
D
16
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