Question

The nth element of the sequence-1,2,-4,8..... is

Answer 1

here

a = -1

d = 2- (-1)

d = 3

last term n = 8

an = a + (n-1)d

an = -1 + ( 8-1 ) 3

an = -1 + 7(3)

an = -1 + 21

an = 20