pq+1) Q. 10. If pth term of an A.P be 1/q and the qth term be 1/p, show that the sum of pq terms is 2 Q. 11. The sum of n terms of an A.P. is given by Sn = 5n + 3n, find the nth term of A.P. Q. 12. How many terms of the A.P. -6, -11/2, -5...........are needed to give the sum -25? Explain the double answer. Q. 13. Find the 30th and 60th terms of the following sequence: a. 13, 18, 23, 28, 33........... b. 10, -7, -4, -1... Q. 14. Find the sum of the following series: a. 3+8+13+18+23 ..248 b. 10, 15, -20, -25,.............-105 Q. 15. The sum of three numbers which are in A.P. is 9 and sum of their squares is 35. Find the numbers.