Question

sum of the first 20 terms of the ap, 5,10,15,20...100

Answer 1

1050

Answer 2

The given sequence is an arithmetic progression with the first term $a_1 = 5$ and common difference $d = 5$. We need to find the sum of the first 20 terms ($n=20$). Using the formula for the sum of the first $n$ terms of an AP, $S_n = \frac{n}{2} [2a_1 + (n-1)d]$, we substitute the values: $S_{20} = \frac{20}{2} [2(5) + (20-1)5] = 10 [10 + 19 \times 5] = 10 [10 + 95] = 10 [105] = 1050$.