Question

obtenha a soma dos termos da P A (-10,-5,0,5,10,15,20)

Answer 1

a₁ = - 10

a₇ = 20

n = 7

Sn = [(a₁ + an). n]/2 ------ S₇ = [(-10 + 20) . 7]/2 ------ S₇ = [(10). 7]/2

S₇ = 70/2 ----- S₇ = 35