What is the sum of the progression 4, 9, 14, 19, . . . . . up to the $20^{th}$ term? Click to Show/Hide Solution \[ S_n = \frac{n}{2}[2a_1 + (n - 1) d] \] \[ S_{20} = \frac{20}{2}[2(4) + (20 - 1) (5)] \] \[ S_{20} =1030 \leftarrow \text{answer} \]
