TOP 100+ Sequences And Series Class 11 NCERT Question and Answers

These Sequences And Series Class 11 NCERT Question and Answers are most important for your upcoming examinations including JEE Main & JEE Advanced. These Sequences And Series Class 11 NCERT Question and Answers will help you to score good marks in your exams by helping you to prepare the concepts better and hence, help you to understand the concepts more clearly.

Sequences And Series Class 11 NCERT Question and Answers

1. If a is the A.M. of b and c and G1 and G2 are two GM between them then the sum of their cubes is

(A) abc

(B) 2abc

(C) 3abc

(D) 4abc

Answer: 2abc


2. Let Sn denote the sum of the first n terms of an A.P. If S2n = 3Sn, then S3n : Sn is equal to

(A) 4

(B) 6

(C) 8

(D) 10

Answer: 6


3. If a, b, c are in A.P., then a3 + c3 − 8b3 is equal to

(A) 2abc

(B) 6abc

(C) 4abc

(D) None of these

Answer: None of these


4. If the roots of the equation a(b − c)x2+ b(c − a)x + c(a − b) = 0 are equal, then a, b, c are in

(A) A.P.

(B) .G.P.

(C) H.P.

(D) None of these

Answer: H.P.


5. If b + c, c + a, a + b are in H.P., then a2, b2, cwill be in

(A) G.P.

(B) H.P.

(C) A.P.

(D) None of these

Answer: A.P.


6. If in an A.P., Sn = qn2 and Sm = qm2, where Sr denotes the sum of r terms of the AP, then Sq equals

(A) q3/2

(B) mnq

(C) q3

(D) (m+n)q2

Answer: q3


7. If 9 times the 9th term of an A.P. is equal to 13 times the 13th term, then the 22nd term of the A.P. is

(A) 0

(B) 22

(C) 198

(D) 220

Answer: 0


8. If the third term of G.P. is 4, then the product of its first 5 terms is

(A) 43

(B) 44

(C) 45

(D) none of these

Answer: 45


9. If the sum of n terms of an A.P. is given by Sn = 3n + 2n2, then the common difference of the A.P. is

(A) 3

(B) 2

(C) 6

(D) 4

Answer: 4


10. If the product of three positive real numbers say a, b, c be 27, then the minimum value of ab + bc + ca is equal to

(A) 274

(B) 273

(C) 272

(D) 27

Answer: 27


11. log45 , log20 5, log1005 are in

(A) A.P.

(B) G.P.

(C) H.P.

(D) None of these

Answer: A.P.


12. Let a, b and c be positive real numbers such that a + b + c = 6. Then range of ab2c3 is

(A) (0, ¥)

(B) (0, 1)

(C) (0, 108]

(D) (6, 108]

Answer: (0, 108]


13. Let p, q, r Î R+ and 27pqr ³ ( p + q + r)3 and 3p + 4q + 5r = 12 then p3 + q4 + r5 is equal to

(A) 3

(B) 6

(C) 2

(D) None of these

Answer: 3


14. If the sum Sn of n terms of a progression is a cubic polynomial in n, then the progression whose sum of n terms is Sn – Sn-1 is

(A) An A. P.

(B) A G. P.

(C) A H.P.

(D) An A. G. P.

Answer: An A. P.


15. If a, b, c are in H.P. and a > c > 0 , then 1/b-c – 1/a-b

(A) Is positive

(B) Is zero

(C) Is negative

(D) Has no fixed sign.

Answer: Is positive


16. Let the positive numbers a, b, c, d be in A.P. then abc, abd, acd, bcd are

(A) Not in A.P./G.P./H.P.

(B) In A.P.

(C) In G.P.

(D) In H.P.

Answer: In H.P.


17. Three non-zero numbers a, b and c are in A.P.. Increasing a by 1 or increasing c by 2 the number become in G.P., then ‘b’ equals to

(A) 10

(B) 12

(C) 14

(D) 16

Answer: 12


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