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A-level Maths - How would you start to draw this reciprocal graph...??

Ok, so I'm having a silly moment and am having trouble drawing this graph...

y=2x+1x2y=\frac{2x+1}{x-2}

I know that the bottom part of the fraction translates the graph to the right by 2 as it "tends to infinity" on the x-axis at x=2.
And that the bottom part of the graph crosses the axis at (12,0)(-\frac{1}{2},0) and (0,12)(0,-\frac{1}{2}).

But I don't know how to draw the rest of the graph properly.
Where on the y-axis does the reciprocal graph "tend to infinity"?
Original post by Philip-flop
Ok, so I'm having a silly moment and am having trouble drawing this graph...

y=2x+1x2y=\frac{2x+1}{x-2}

I know that the bottom part of the fraction translates the graph to the right by 2 as it "tends to infinity" on the x-axis at x=2.
And that the bottom part of the graph crosses the axis at (12,0)(-\frac{1}{2},0) and (0,12)(0,-\frac{1}{2}).

But I don't know how to draw the rest of the graph properly.
Where on the y-axis does the reciprocal graph "tend to infinity"?


Divide top by bottom to get it in the form y=2 + A/(x-2)
Reply 2
It may be easier to sketch if you write y as 2+5x2 2+\frac{5}{x-2} .
From here it is easy to see that the curve is just 1/x with a few simple transformations applied.
Original post by tiny hobbit
Divide top by bottom to get it in the form y=2 + A/(x-2)


Can you explain the process of dividing the top by the bottom? I don't think I'm following :frown:

I ended up with y=2+1x2y=-2+\frac{1}{x-2}

I think I did something wrong? :frown:
(edited 7 years ago)
Reply 4
Original post by Philip-flop
Can you explain the process of dividing the top by the bottom? I don't think I'm following :frown:

I ended up with y=2+1x2y=-2+\frac{1}{x-2}

I think I did something wrong? :frown:



Basic long division, you should be able to do since you did chapter 1!
Reply 5
2x+1x2=2(x2)+5x2=2+5x2\frac{2x+1}{x-2} = \frac{2(x-2)+5}{x-2} = 2+\frac{5}{x-2}
(edited 7 years ago)
Original post by Naruke
Basic long division, you should be able to do since you did chapter 1!


Oh yeah! I didn't think about dividing in that way! Managed to work out the answer straight away with the long division method.

Original post by solC
2x+1x2=2(x2)+5x2=2+5x2\frac{2x+1}{x-2} = \frac{2(x-2)+5}{x-2} = 2+\frac{5}{x-2}

Thank you :smile:

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