# domain and range-test in two weeks yr 11

• May 12th 2008, 02:54 AM
fareezuh
domain and range-test in two weeks yr 11
how do you find the domain and range of a hyperbola, parabola, linear, circular,exponantial and semicircle graph??????
any help appreacited.
• May 12th 2008, 03:15 AM
Moo
Hello,

Quote:

Originally Posted by fareezuh
how do you find the domain and range of a hyperbola, parabola, linear, circular,exponantial and semicircle graph??????
any help appreacited.

Do you have examples ?
In general, how to find the domain of a function ?
- not defined at points which annulate a denominator
- not defined at points which make a number under a square root negative

.. I don't see any other for the moment at your level...

In order to find the range, the best to do is to graph the function...

It'd be easier to show you methods in examples since these methods highly depend on the function...
• May 12th 2008, 03:28 AM
fareezuh
examples
absolute value graphs-
find :
domain and range
if y(x)

parabola -domain&range
if y=xsquared-4

hyperbola xy=1
find domain & range

cubic curve y=xcubed

i understand that domain is the number of x values that the graph <sketch> will cover but what is the range and how do you find out
thanks
• May 12th 2008, 03:31 AM
Moo
Quote:

i understand that domain is the number of x values that the graph <sketch> will cover but what is the range and how do you find out
The range is sort of the domain, but for y.

I found a method :

$y(x)=x^2-4$

-> $x=\pm \sqrt{y+4}$

Which is defined if $y+4 \geq 0$, this will give the range :-)
• May 12th 2008, 03:40 AM
fareezuh
yes i lack mathamtical intelect
do cubics have a domain and range
???????
• May 12th 2008, 03:42 AM
Moo
Quote:

Originally Posted by fareezuh
do cubics have a domain and range
???????

For $x^3$ the domain and the range are both all real numbers ;)

You can find domain and range by referring to a reference function, such as square root, x², 1/x etc...