Question

For the following arithmetic sequence, find the value of a and d and hence find the term indicated: - 2 , 2 , 6 , 10 , . . . , t 7. If the first term of an arithmetic sequence is 7 and the 4th term is 28, find the value of d.

Answer 1

`t_(7)` = 22 is the answer to the first question

d = 4 is the answer to the second question

Explanation:

use the formula
`a_(n) = a + (n - 1)d`

6 - 2 = 4 = d a = -2 n = 7

`t_(7)` = -2 + (7 - 1)4

= -2 + 6(4)

= -2 + 24

= 22

use the formula
`a_(n) = a + (n - 1)d`

a = 7

n = 4

`a_(4) = 28`

28 = 7 + (7 - 1)d

= 4 + 6d

24 = 6d

d = 4