Question

Write three arithmetic sequences with sum of the first five terms as 40

Answer 1

Answer:

sum(5) = (5/2)(2a + 4d) = 30

2a + 4d = 12

a + 2d = 6

a = 6-2d

so we can assign any value to d

e.g. d = 7

then a = 6-14 = -8

one possible sequence is:

-8 , -1, 6, 13, 20

(their sum is 30)

let d = 3

a = 6-6 = 0

terms are:

0, 3, 6, 9, 12

(their sum is 30)