Thread: Trouble with graphi and asymptotes

4. a) Find all horizontal and vertical asymptotes of f(x)= -x / (x+1)(x-3) and sketch it's graph.

There should be two vertical asymptotes, x=-1 and x=3. I used multiple graph calculators online and they do not show the x=3 asymptote.

What am I doing wrong?

Originally Posted by thekrown

4. a) Find all horizontal and vertical asymptotes of f(x)= -x / (x+1)(x-3) and sketch it's graph.

There should be two vertical asymptotes, x=-1 and x=3. I used multiple graph calculators online and they do not show the x=3 asymptote.

What am I doing wrong?

most calculators will not show the asymptotes because there is a hole in the function. there may appear to be an asymptote sometimes due the screen resolution and a jump from a long distance between points.

Okay so am I correct with this answer:

Horizontal Asymptote
when x gets big+ y gets close to 0-
when x gets big- y gets close to 0+

Vertical Asymptote
x gets close to 3+ y gets big -
" " " " 3- y gets big +
" " " " -1+ y gets big -
" " " " -1- y gets big +

yes it appears so

if you haven't ever used this you might like

- Wolfram|Alpha

where I graphed your equation

this ussually gives more info about what's going on.

Thanks for your help, it's good to know I'm not crazy after all.