Question

Calcule a soma dos 50 primeiros termos da p.a ( 1,5/2)

Answer 1

Vamos lá:
$a_1 = 1; a_2 = \frac{5}{2} \\\ r = \frac{5}{2} - 1 \\\ r = \frac{3}{2} \\\ a_{50} = a_1 + 49r \\\ a_{50} = 1 + 49.\frac{3}{2} \\\\ a_{50} = 74,5 \\\ S_{50} = \frac{(a_1 + a_{50}).50}{2} \\\\ S_{50} = (1 + 74,5).25 \\\ S_{50} = 1887,5$

Espero ter ajudado.