# How do you find the domain and range of #y=2^(-x)#?

##### 1 Answer

May 9, 2017

The domain is

#### Explanation:

Given:

#y = 2^(-x)#

First note that this is well defined for any real value of

So the domain is the whole of

Next note that

Let

#log(y) = log(2^(-x)) = (-x) log(2)#

Dividing both sides by

#x = -log(y)/log(2)#

So that tells us that for any

#y = 2^(-x)#

So the range is the whole of