At a club each member shook hands with every other member. If there were totally 190 handshakes , how many members were present?
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nC2 = n(n-1)/2
190= n ( n-1)/2
380= n ( n-1)
380= n^2 - n
n^2- n -380 = 0
n^2 - 20n + 19n - 380= 0
n ( n - 20) + 19 ( n - 20) = 0
(n + 19) ( n - 20) =0
we get 2 values of n that is - 19 and 20. But people can't be negative.
Therefore there were 20 people
190= n ( n-1)/2
380= n ( n-1)
380= n^2 - n
n^2- n -380 = 0
n^2 - 20n + 19n - 380= 0
n ( n - 20) + 19 ( n - 20) = 0
(n + 19) ( n - 20) =0
we get 2 values of n that is - 19 and 20. But people can't be negative.
Therefore there were 20 people
SARDARshubham:
wlc!!!
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