Sequences and Series
Find the sum to n terms of the series :1×2×3+2×3×4+3×4×5+˙˙˙
200 logs are stacked in the following manner: 20 logs in the bottom row, 19 in the next row, 18 in the row next to it and so on (see Figure). In how may rows are the 200 logs placed and how many logs are in the top row?
If the sum of n terms of an A.P. is nP+21n(n−1)Q,where P and Q are constants, find the common difference.
Write the first three terms in each of the following sequences defined by the following:(i) an=2n+5 (ii) an=4n−3
A mail starts repaying a loan as first instalment of Rs. 100. If he increases the instalment by Rs 5 every month, what amount he will pay in the 30thinstalment?