AP

The formulas for the sum of the first $n$ terms of an AP are: 1. Find the Sum of the following APs (i) $2, 7, 12, \dots$, to 10 terms. $a=2, d=5, n=10$. $$S_{10} = \frac{10}{2}[2(2) + (10-1)5]$$ $$S_{10} = 5[4 + 9(5)] = 5[4 + 45] = 5(49) = \mathbf{245}$$ (ii) $-37, -33, -29, … Read more