A) \[\frac{x\ !\ y\ !}{r\ !}\]
B) \[\frac{(x+y)\ !}{r\ !}\]
C) \[^{x+y}{{C}_{r}}\]
D) \[^{xy}{{C}_{r}}\]
Correct Answer: C
Solution :
The result is trivially true for\[r=1,\ 2\]. It can be easily proved by the principle of mathematical induction that the result is true for \[r\] also.You need to login to perform this action.
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