Question

2, -3, -8, -13, -18,

Answer 1

Explanation:

2, -3 , -8 , -13 , - 18 .............

This is an arithmetic sequence.

First term = a = 2

Common difference = Second term - first term

= -3 - 2 = -5

Nth term = a + (n - 1)*d

= 2 + (n - 1)*(-5)

= 2 + n*(-5) - 1 *(-5)

= 2 - 5n + 5

= 7 - 5n

n = 19,

19th term = 7 - 5*19

= 7 - 95

= - 88

n = 21,

21st term = 7 - 5*21

= 7 - 105

= -98