Maths · Algebra · chapter 8 of 14

Class 11 Maths Chapter 8: Sequences and Series Assertion-reason questions with answers

2 assertion-reason questions on Sequences and Series, each with its answer and the reason, written from the NCERT chapter. For school exams on the CBSE pattern and JEE Main, which are set from the same NCERT chapter. Open a question's solution to check your working; then take the free test to find your next chapter. Each question gives an Assertion (A) and a Reason (R); choose how they stand to each other.

Question 1
Assertion (A): The sequence 5, −5, 5, −5, … is a G.P. Reason (R): A sequence of non-zero terms is a G.P. when the ratio of each term to the term before it is the same throughout.
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Answer: (a) Both A and R are true, and R is the correct explanation of A.

Every term is non-zero and each ratio is −1, a constant, which is exactly the definition in R; so R explains A.

Question 2
Assertion (A): 2 + 4 + 6 + … + 40 is a finite series. Reason (R): The series associated with an infinite sequence is an infinite series.
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Answer: (b) Both A and R are true, but R is not the correct explanation of A.

A is true: the series has 20 terms. R is true too, but it speaks of infinite sequences; A holds because the sequence 2, 4, …, 40 is finite, which R does not say.

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