Question

How many terms are in arithmetic sequence whose first term is -3, common difference is 2,and last term is 23

Answer 1

a = -3,

d = 2,

last term, l = 23

a + (n - 1)*d

23 = a + (n - 1)d

23 = -3 + (n -1)2

23 + 3 = 2(n - 1)

26 = 2(n - 1)

2(n - 1) = 26

n - 1 = 26/2

n - 1 = 13

n = 13 + 1

n = 14

There are 14 terms.