CBSE Class 10 Maths Sample Question Paper 2019 | Q8

This 2019 CBSE class 10 Maths sample question paper 2 mark question is from arithmetic progressions. Concept: nth term of an arithmetic progression. An easy question.

Question 8B: If 7 times the 7th term of an A.P is equal to 11 times its 11th term, then find its 18th term.

Video Explanation

Explanatory Answer | 2019 Sample Question Paper 8B

Step 1 : Represent the terms in terms of the first term and common difference

7th term, a₇ = a + 6d
11th term, a₁₁ = a + 10d
18th term, a₁₈ = a + 17d

Step 2 : Apply the condition given in the question

7 times 7th term = 11 times 11th term
7(a + 6d) = 11(a + 10d)
7a + 42d = 11a + 110d
4a + 68d = 0
a + 17d = 0 or a₁₈ = 0