Expert: Bobby Soltani - 12/6/2005

Question
How do we do these problems?

y=1
____               
 x + 2

y=1
____
 3x

Answer
Hi Ty,

The domain of a function is all values of x where the function is defined.  When you have functions with x in the denominator, you need to determine for what values of x the denominator is 0.  The reason for this is that anything divided by zero is undefined.

y = 1/(x + 2)

Set the denominator equal to zero to see where the function is undefined.

x + 2 = 0

x = -2

Therefore the domain is all values of x, except x = -2

y = 1/(3x)

3x = 0

x = 0

Domain is all values of x, except x = 0

Let me know if you have any questions.

Bobby