Ans: D
given expression looks a bit ... you know what i mean: so lets make it easy lets say that first number in ! is x so expression will become
\((x!)((x+1)! + x!)\) from here.. let me also write !x as F(x)
If we take the F(x) inside, expression will become [F(x)*F(x+1) + F(x)^2]
We know F(x+1) = (x+1)*F(x)
so it becomes [F(x)^2 * (x+1) + F(x)^2]
npw take F(x)^2 common Expression will become = F(x)^2 [x+1+1]
F(x)^2 [x+2]
now we need to know if this is whole square or not. We know F(x)^2 is always so we just need to know if (x+2) is whole square or not.
Put x =23 , we know 25 is a whole square so D is the ans.
Bunuel wrote:
Which of the following numbers is a perfect square?
A. \((20!)(21! + 20!)\)
B. \((21!)(22! + 21!)\)
C. \((22!)(23! + 22!)\)
D. \((23!)(24! + 23!)\)
E. \((24!)(25! + 24!)\)
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