Q. 2. If a1, a2, a3, a4, a4,…… are the n terms of an A.P. Derive the formula for the sum of its n terms.

Q. 3. If nth term of an A.P. is given by an = 5n – 3. Find the sum of its 50 terms.

Q. 4. Sum of n terms of a sequence is given by Sn = 2n2 – 2n. If it is an A.P. then find its 20th term.

Q. 5. Find the sum of the following series: 10 + 14 + 18 + 22 + …………104

Q. 6. If the sum of first 13 terms of an A.P. is 91 and sum of its first 30 terms is 465. Find the sum of its 50 terms.

Q. 7. The sum of three numbers which are in A.P. is 9 and sum of their squares is 35. Find the numbers.

Q. 8. Divide 32 into 4 parts such that they are in AP and the ratio of the product of first term and fourth terms = product of second and third terms is equal to 7/15.

Q. 9. If the pth,qth,rth terms of an AP are a,b,c then prove a(q – r) + b(r-p) = c (q – p)

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

Q. 11. The sum of n terms of an A.P. is given by Sn = 5n2 + 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:

(1) 13, 18, 23, 28, 33,………. (2) -10, -7, -4, -1……………..

Q. 14. Find the sum of the following series: (1.) 3+8+13+18+23 …………………….248

(2). -10, -15, -20, -25,………….-105

Q.15 If Sn, the sum of first n terms of an A.P is given by Sn = 3n2 – 4n, then find its nth term (6n – 7)

10th Arithmetic progression (6 Posts)