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posted by Shay on Monday, August 25, 2008 at 4:49pm.

seven people meet and shake hands with eachother- how many handshakes occur? (second question) using inductive reasoning, write a formula for the number of handshakes if the number of people is n

combinations of n objects taken r at a time C(n,r) = n!/[r!(n-r!)] C(7,2) = 7!/[2!(5!)] =7*3 =21 ok, reasoning first person shakes with 6 second person with 5 third with 4 . . . 6th with 1 so 6+5+4+3+2+1 = 21 sure enough

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