Question

calcule a soma dos 51 termos da p.a -16,-14,-12,84

Answer 1

n = 51
a1 = - 16
a2 = - 14
a3 = - 12

r = -14 - ( -16 ) = -14 + 16 = 2 ****
a1 + 50r = -16 + 50(2)  = -16 + 100 = 84

S51 = ( -16 + 84). 25.5
S51 = 68 . 25.5 = 1734 *****