Math

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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

  • Math -

    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

  • Math -

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