Permutations And Combinations Question 47
Question: If $ x,\ y $ and $ r $ are positive integers, then $ ^{x}C _{r}{{+}^{x}}{C _{r-1}}^{y}C_1{{+}^{x}}{C _{r-2}}^{y}C_2+…….{{+}^{y}}C _{r}= $ [Karnataka CET 1993; RPET 2001]
Options:
A) $ \frac{x\ !\ y\ !}{r\ !} $
B) $ \frac{(x+y)\ !}{r\ !} $
C) $ ^{x+y}C _{r} $
D) $ ^{xy}C _{r} $
Correct Answer: C
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Answer:
Solution:
BETA
