# What is the domain and range of #y = - sqrt(9-x^2)#?

##### 1 Answer

Domain:

Range:

#### Explanation:

In order to find the function's domain, you need to take into account the fact that, for real numbers, you can only take the square root of a **positive number**.

In other words, in oerder for the function to be defined, you need the expression that's under the square root to be positive.

#9 - x^2 >= 0#

#x^2 <= 9 implies |x| <= 3#

This means that you have

#x >= -3" "# and#" "x<=3#

For any value of *negative*, which means that the function will be undefined. Therefore, the domain of the function will be

Now for the range. For any value of **negative**.

The *maximum* value the expression under the radical can take is for

#9 - 0^2 = 9#

which means that the *minimum* value of the function will be

#y = -sqrt(9)= -3#

Therefore, the range of the function will be

graph{-sqrt(9-x^2) [-10, 10, -5, 5]}