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yclicc
New poster

Post Number: 1
Posted on Tuesday, 24 April, 2012 - 08:35 pm:   

[display]f(x)=x-4-\frac{16(2x+1)^2}{x^2 * (x+4)}[/display]

State vertical and oblique asymptotes (x=0,4, y=x) and show that the oblique asymptote is tangent to the curve.

I have tried proving it is tangent by setting f(x)=x and trying to show there is a repeated root, but I get a horrible cubic: x^3+20x^2+16x+4=0 . Then, when I cheat and type the equation into wolfram alpha, it appears part 2, show that f(x)=0 has a double root, isn't true...

http://www.admissionstests.cambridgeassessment.org.uk/adt/digitalAssets/107041_2004.zip

is the link to the paper...can anyone offer any suggestions?
biffboy
Regular poster

Post Number: 67
Posted on Wednesday, 25 April, 2012 - 07:10 am:   

Your working suggest the asymptote isn't y=x
Andre Rzym
Veteran poster

Post Number: 1796
Posted on Wednesday, 25 April, 2012 - 12:19 pm:   

Either one of your stated vertical asymptotes is incorrect, or your original statement of [inline]f(x)[/inline] has a typo (and [inline]y=x[/inline] is not quite the oblique asymptote).

Andre
Rahulllll
Poster

Post Number: 7
Posted on Wednesday, 25 April, 2012 - 07:28 pm:   

seems like you took your oblique asymptote as y=x which isnt completely accurate.

look at the way f(x) has been written again- it is giving you a big hint.

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