Neha Tyagi and Amit Rastogi Solutions for Chapter: Arithmetic Progressions, Exercise 1: Exercise

Two arithmetic progressions have the same common difference. The first term of one is $-1$ and that of the other is $-8$. The difference between their $4^{\mathrm{th}}$ terms is 

If $7$ times the $7^{\mathrm{th}}$ term of an A.P. is equal to $11$ times its ${11}^{\mathrm{th}}$ term, then its ${18}^{\mathrm{th}}$ term will be 

The $4$^th term from the end of an $\mathrm{A}.\mathrm{P}., -11, -8, -5, ..., 49$ is

The famous mathematician associated with finding the sum of the first $100$ natural numbers is 

If the first term of an $\mathrm{AP}$ is $-5$ and the common difference is $2$, then the sum of the first $6$ terms is 

The sum of first $16$ terms of the $\mathrm{A}.\mathrm{P}., 10, 6, 2,....$is

In an $\mathrm{AP}$, if $a=1$, $a_n=20$ and $S_n=399$, then $n$ is equal to 

The sum of first five multiples of $3$ is