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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Specialist Mathematics => Topic started by: tram on October 12, 2010, 06:48:25 pm

Title: asymptote question
Post by: tram on October 12, 2010, 06:48:25 pm
what would you say the asymptotes for the graph

(x^3 - 1)/ x

are?

(soz for the lack of latex)
Title: Re: asymptote question
Post by: Souljette_93 on October 12, 2010, 06:58:04 pm
Wouldn't it be and ?
Title: Re: asymptote question
Post by: Martoman on October 12, 2010, 08:20:40 pm
I usually work with limits.



as x gets very big or very big negatively the 1/x fraction becomes stupidly close to 0 as the 1/x graph has an asymptote there. The other reasoning if you don't like looking at it graphically is that so small in fact that its negligeable. so y approaches x^2 as x is very big in the negative or positive direction. The other asymptote to obserive is if x= 0, as that would mean the 1/x term is 1/0 ie undefined.
Title: Re: asymptote question
Post by: tram on October 12, 2010, 09:28:00 pm
yeah, see my think was EXACTLY what both of you guys said, only i had a srsly lengthy discission with my friends about whether or not y= -1/x was also an asymptote. I said that the asymptote x=0 covered this but they insisted that it was necessary. Opinions????
Title: Re: asymptote question
Post by: brightsky on October 12, 2010, 09:58:49 pm
yeah, see my think was EXACTLY what both of you guys said, only i had a srsly lengthy discission with my friends about whether or not y= -1/x was also an asymptote. I said that the asymptote x=0 covered this but they insisted that it was necessary. Opinions????

Hmm..I think it's clear enough from the graph that y = -1/x isn't an asymptote. Also, it doesn't correlate to any of the usual techniques used to find asymptotes. Are you able to provide the reasoning behind their answer?
Title: Re: asymptote question
Post by: tram on October 13, 2010, 05:51:51 pm
well, it had to do with the fact that you were effectively adding ordinates and thus as x approaches 0, then obvsiously x^2 approaches zero, and that means that the graph is apporaching whatever -1/x is => it is an asymptote.
Title: Re: asymptote question
Post by: brightsky on October 13, 2010, 07:47:02 pm
well, it had to do with the fact that you were effectively adding ordinates and thus as x approaches 0, then obvsiously x^2 approaches zero, and that means that the graph is apporaching whatever -1/x is => it is an asymptote.

Why let x tend to zero?
Title: Re: asymptote question
Post by: supernatural on October 13, 2010, 07:48:00 pm
i think it would be and

the same question was in the mav 2010 trial. thats what the answers say as well.

because when x -> ∞  f(x) ->    but doesn't touch it, meaning its an asymptote
and x cannot be zero too, so that's an asymptote as well

I said that the asymptote x=0 covered this

i think so as well. when x-> 0 [from the left or right]  f(x)->

and what are the asymptotes for ?  x = 0

so x=0 covers this i guess