10) The nth term of an arithmetic sequence is given by an = a + ( n - 1 )d where a is the 1st term and d is the common difference. Which term of the arithmetic sequence 1, 4, 7, ....... is 88? 1- rn 11) The partial sum of a geometric sequence is given by Sn = a where a is the 1st term an 1 -r r is the common ratio. Find the sum of the sequence 1 + 3 + 9 + ........ + 2187