Question

determine a soma dos 50 primeiros termos da PA (5, 10, 15)​

Answer 1

$a_{50} = 5 + 49 \times 5 \\ a_{50} = 250$

$S_{50} = \frac{(5 + 250) \times 50}{2} \\ S_{50} = 255 \times 25 \\ S_{50} = 6375$