Find the sum of the first 21 terms of the A .P. whose 2nd terms is 8 and 4th term is 14.
The sum of the first n terms of an A .P. is given by Sn = 3n2 + 2n. Determine the A .P. and its 15th term.
Solution not provided.
Ans. 5, 11, 17, 23;, T15 = 89
The sum of the first n terms of an A .P. is given by Sn = 3n2 + 2n. Determine the A .P. and its 15th term.