Question

Write an expression to describe the sequence below. Use n to represent the position of a term in the sequence, where n = 1 for the first term.

10, 11, 12, 13

Answer 1

`9 + n`

Explanation:

Well it's an arythmetic sequence, so it will look like:

`a + d\cdot n`

Note that the first element is:

`a + d\cdot 1`

and the second element is:

`a + d \cdot 2`

So the difference between the two gives us d!

`d = 11 - 10 = 1`

Now let's find the
`a`:

`a + d\cdot 1 = 10\\a + 1 \cdot 1 = 10\\a + 1 = 10\\a = 9`