Question

numa pa onde 20 termo e 157 e 1 termo e 5 , calcule a razão

Answer 1

An = A1 + ( N - 1 ) * r

an = a 20 = 157
a1 = 5
n = 20
r = x

157 = 5 + ( 20 - 1) * r
157 = 5 + 19 * r
157 = 24r

 157 = r
  24

r = 6,54

Answer 2

A1 = 5
a20 = 157
formA geral da PA :

an = a1 + ( n - 1 ) r
a20 = 5 + ( 20 -1 ) r
157 = 5 + 19r
157-5 = 19r
152=19r
r = 152/19
r = 8