Assume there are 20 people in a room, including you. You must shake hands with everyone else in the room. How many hands will yo
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Answer:
= 2n - 3
Step-by-step explanation:
Note the difference in consecutive terms is constant, that is
1 - (- 1) = 3 - 1 = 5 - 3 = 7 - 5 = 2
This indicates that the terms are an arithmetic sequence with
= a₁ + (n - 1)d
where a₁ is the first term and d the common difference
Here a₁ = - 1 and d = 2, thus
= - 1 + 2(n - 1) = - 1 + 2n - 2 = 2n - 3