# graph function

• Oct 17th 2010, 07:55 AM
wolfhound
graph function
Hi,
How would I graph this function please?

$y=-x^2/(2-x+4)$
• Oct 17th 2010, 10:08 AM
skeeter
Quote:

Originally Posted by wolfhound
Hi,
How would I graph this function please?

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

what you posted is equivalent to $\displaystyle y = \frac{x^2}{x-6}$

or did you really mean this ...

$\displaystyle y = -\frac{x^2}{2x^2 - x + 4}$

?
• Oct 17th 2010, 10:32 AM
wolfhound
Quote:

Originally Posted by skeeter
what you posted is equivalent to $\displaystyle y = \frac{x^2}{x-6}$

Hi, its this one, but I dont know what to do?
• Oct 17th 2010, 10:53 AM
skeeter
graph has a vertical asymptote and a slant asymptote ... start by finding and graphing them.
• Oct 17th 2010, 11:30 AM
wolfhound
i don't know how sorry
• Oct 17th 2010, 12:12 PM
earboth
Quote:

Originally Posted by wolfhound
i don't know how sorry

Use long division:

Code:

                                    36   x^2          ÷ (x - 6) = x + 6 + ----- -(x^2 - 6x)                          x-6 -------------         6x       -(6x - 36)       ----------             36
That means: $y = \dfrac{x^2}{x-6} = \underbrace{x + 6}_{\text{term of slant asymptote}} + \dfrac{36}{x-6}$

Keep in mind that a denominator must unequal zero.
• Oct 17th 2010, 12:33 PM
wolfhound
Quote:

Originally Posted by earboth
Use long division:

Code:

                                    36   x^2          ÷ (x - 6) = x + 6 + ----- -(x^2 - 6x)                          x-6 -------------         6x       -(6x - 36)       ----------             36
That means: $y = \dfrac{x^2}{x-6} = \underbrace{x + 6}_{\text{term of slant asymptote}} + \dfrac{36}{x-6}$

Keep in mind that a denominator must unequal zero.

Oh thanks, but I still don't know how to graph it
• Oct 17th 2010, 01:42 PM
skeeter
Quote:

Originally Posted by wolfhound
Oh thanks, but I still don't know how to graph it

have you had any instruction on the graphing of rational functions? if not, then you need to research the topic and do some example problems.

here's a link to get you started ...

http://www.mathmotivation.com/lectur...-Functions.pdf
• Oct 17th 2010, 02:24 PM
wolfhound
No ,I haven't been taught anything about the graphing of them. The question I got asked me to identify if the parabola is U or n shaped.( i know -x^2 means n shape)
But i want to understand the whole concept of it... thanks
• Oct 17th 2010, 02:36 PM
skeeter
Quote:

Originally Posted by wolfhound
Hi,
How would I graph this function please?

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

where did this original equation come from?
• Oct 17th 2010, 11:19 PM
wolfhound
on the question sheet :)