###
function

a relationship between numbers where each number in the domain corresponds to exactly one number in the range

###
sequence

a function whose domain is the set of all positive integers

###
y=f(x)

formula for a sequence

###
t sub n = t₁ + (n-1)d

explicit formula for an arithmetic sequence

###
state a term; t sub n = t sub (n-1) +d

recursive formula for an arithmetic sequence

###
t sub n = t₁ * rⁿ⁻¹

explicit formula for a geometric sequence

###
state a term; t sub n = t sub (n-1) * r

recursive formula for a geometric sequence

###
S sub n = n [(t₁ + t sub n)/2]

formula for the sum of the first n terms in an arithmetic sequence

### Please allow access to your computer’s microphone to use Voice Recording.

## We can’t access your microphone!

### Click the icon above to update your browser permissions and try again

Example:

### Reload the page to try again!

Reload

## Press Cmd-0 to reset your zoom

## Press Ctrl-0 to reset your zoom

### It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

## Your microphone is muted

### For help fixing this issue, see this FAQ.