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# asymptotes - C1 Edexcel Watch

1. Hey guys I have a question . Its for C1 EDEXCEL

Im totally confused about asymtotes.

QUESTION 1 : Firstly what are they?

Secondly i dont get this example in the book

I get the sketch bit the part I dont know how to "state the equations of any asymptotes and intersections with the axes"

"The curve crosses the x-axis once. " "y = h(x) + 1 = 1/x + 1"

QUESTION 2: did they add the 1 because the curve crosses the x-axis once or is it because the graph has been translated +1 along the y-axis???

QUESTION 3: Can someone please explain the below three lines, how did they get theses values?:

" so the curve intersects the x-axis at (-1,0)."

"the horizontal asymptote is y=1"

"the vertical asymptote is x=0"

thanks
2. (Original post by jayseanfan)
Hey guys I have a question . Its for C1 EDEXCEL

Im totally confused about asymtotes.

Q1 Firstly what are they?

Secondly i dont get this example in the book

I get the sketch bit the part I dont know how to "state the equations of any asymptotes and intersections with the axes"

"The curve crosses the x-axis once. " "y = h(x) + 1 = 1/x + 1"

Q2) did they add the 1 because the curve crosses the x-axis once or is it because the graph has been translated +1 along the y-axis???

Q3) I dont get the whole bit, can someone please explain all three lines:

" so the curve intersects the x-axis at (-1,0)."

"the horizontal asymptote is y=1"

"the vertical asymptote is x=0"

thanks
an asymptote is a line which a curve bends towards but never reaches it.

in this case, y=0 and x=0 and solve

to find out where it crosses the x-axis, put y=0
the y-axis: x=0 and solve
3. (Original post by jayseanfan)
Hey guys I have a question . Its for C1 EDEXCEL

Im totally confused about asymtotes.

QUESTION 1 : Firstly what are they?

Secondly i dont get this example in the book

I get the sketch bit the part I dont know how to "state the equations of any asymptotes and intersections with the axes"

"The curve crosses the x-axis once. " "y = h(x) + 1 = 1/x + 1"

QUESTION 2: did they add the 1 because the curve crosses the x-axis once or is it because the graph has been translated +1 along the y-axis???

QUESTION 3: Can someone please explain the below three lines, how did they get theses values?:

" so the curve intersects the x-axis at (-1,0)."

"the horizontal asymptote is y=1"

"the vertical asymptote is x=0"

thanks
Hey got your message, happy to help.

Q1) An asymptote is a curve that never crosses the y or x axis's but gets closer and closer to them as the curve stretches to infinity.

Q2) The +1 is because they have now shifted the asymptote +1 in the Y direction. So the equation for the curve was y=1/x, now it is y=1/x +1

Q3) You can see from the diagram the curve crosses the x axis at one point. You know that if you make Y = 0 you can find the X co-ordinate where the curve
crosses.

So the X co-ordinate is -1. We made the Y co-ordinate 0, so the total co-ordinate is (-1,0)

Now for the Horizontal and vertical asymptotes. Again lets look at the diagram. Look at the ends of the curve that seems to be stretching towards infinity. What line do they seem to be trying to get close too? If you draw the line they're trying to get to and read where is crosses the axis's then you'll find the vertical and horizontal asymptotes.

Reply if you need anymore help, i know i may have been a little confusing
4. (Original post by jayseanfan)
Hey guys I have a question . Its for C1 EDEXCEL

Im totally confused about asymtotes.

QUESTION 1 : Firstly what are they?
Asymptotes are lines where the graph never reaches. For example, in the function y = 1/x, when x = 0 then y is undefined (since 0 goes into 1 not even an infinite amount of times). The same applies for y = 0; there are no values of x which make y = 0. Usually, asymptotes feature in functions where dividing by zero is not allowed.

"The curve crosses the x-axis once. " "y = h(x) + 1 = 1/x + 1"

QUESTION 2: did they add the 1 because the curve crosses the x-axis once or is it because the graph has been translated +1 along the y-axis???
h(x) = 1/x, i.e. the function of x defined by h(x) equals one over x. The function changes the input x into 1/x. Adding 1 to the function, we change x into 1/x and then add 1 to the whole thing (this is a somewhat watered-down description of functions). Adding 1 translates it along the positve y-axis.

QUESTION 3: Can someone please explain the below three lines, how did they get theses values?:

" so the curve intersects the x-axis at (-1,0)."

"the horizontal asymptote is y=1"

"the vertical asymptote is x=0"

thanks
The whole graph has moved up 1 in the positive y-axis direction. The point (-1,-1) now is at (-1,0) and intersects the x-axis; the asymptote originally at y = 0 has moved up to y = 1; the vertical asymptote at x = 0 remains unchanged by the translation.
5. gozatron has basically explained what you need to know
but make sure you practise more of these type of questions.

you should know what an asymptotes by now, it was in GCSE but anyways, if you dont understand anything, PM me or reply to this thread again and ill try and explain it
6. Got your message, no point me repeating whats been said already though. Dunno what else to say except once you get the concept, just go through the exercises and practice.

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