i am confused about this one

At a family runion everyone shakes everone elses hand once, if a total of 190 handshakes take place,how many people were at the reunion?

and one more what is a constant ter in the expansion of (x+2)^9

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- May 26th 2005, 04:13 PMkelseycombinatorics
i am confused about this one

At a family runion everyone shakes everone elses hand once, if a total of 190 handshakes take place,how many people were at the reunion?

and one more what is a constant ter in the expansion of (x+2)^9 - May 26th 2005, 05:46 PMaskmemath
IF everybody shook hands atleast once then there were nC2 handshakes since it takes 2 people to shake hands

=> [n(n-1)]/2=190

n(n-1)=380

or n=20

SO 20 people were present