Question

quantos termos tem a PA (15,20,25...160)?

Answer 1

PA (15, 20, 25..., 160)
a1 = 15
r = 5

an = a1 + (n - 1) . r
160 = 15 + (n - 1) . 5
160 = 15 + 5n - 5
160 - 15 + 5 = 5n
150 = 5n
150/5 = n
n = 30 termos