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Lecture - 4 Chapter 9 Sequences & Series

NCERT EXERCISE 9.2

Question 13. If the sum of n terms of an A.P. is $3n^2+5n$ and its m^th term is 164, find the value of m.

Question 14. Insert five numbers between 8 and 26 such that the resulting sequence is an A.P.

Question 15. If $\frac{a^n+b^n}{a^{n-1}+b^{n-1}}$ is the A.M. between a and b, then find the value of n.

Question 16. Between 1 and 31, m numbers have been inserted in such a way that the resulting sequence is an A. P. and the ratio of 7^thand (m – 1)^th numbers is 5 : 9. Find the value of m.

Question 17. A man starts repaying a loan as first installment of Rs. 100. If he increases the installment by Rs 5 every month, what amount he will pay in the 30^th installment?

Question 18. The difference between any two consecutive interior angles of a polygon is 5°. If the smallest angle is 120° , find the number of the sides of the polygon.