The whole number m is a term in an arithmetic sequence with common difference 2. Show that the sum of the term m and the next two terms is a multiple of 3, no matter what the value of m.
ThenSn=n(a1+an)2Sn=n(a1 + an)2 , where nn is the number of terms, a1a1 is the first term and anan is the last term. The sum of the first nn terms of an arithmetic sequence is called an arithmetic series .
