Question

In an arithmetic sequence, the first term,

�
1
,
a
1
​
, is equal to
7
,
7, and the fourth term,
�
4
,
a
4
​
, is equal to
25.
25. Which number represents the common difference of the arithmetic sequence?

Answer 1

The common difference is 6

Explanation:

`a = 7`

`t(4) = 25`

`d = unknown`

`t(n) = a + (n - 1)d`

`t(4) = 7 + (4 - 1)d`

`25 = 7 + 3d`

`25 - 7 = 3d`

`18 = 3d`

divide both sides by 3

`(3d)/(3) = (18)/(3)`

`d = 6`

The numbers are 7,13,18,25.....