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From: agua on 2 Jul 2010 02:57
Hi
With Plot[( (2x+1) Sqrt[x+1] ) / Sqrt[x-1] ,{x,-5,5}]
hoped to obtain a graph only for x>1.

What happened?
regards.

From: Sunt on 2 Jul 2010 07:26
On Jul 2, 2:57 pm, agua <auguayl...(a)gmail.com> wrote:
> Hi
> With Plot[( (2x+1) Sqrt[x+1] ) / Sqrt[x-1] ,{x,-5,5}]
> hoped to obtain a graph only for x>1.
>
> What happened?
> regards.

Hi,
Add PlotRange option in the command Plot like:
Plot[( (2x+1) Sqrt[x+1] ) / Sqrt[x-1] ,{x,-5,5},PlotRange->{1,100}]

From: Bill Rowe on 3 Jul 2010 08:17
On 7/2/10 at 2:57 AM, auguaylupo(a)gmail.com (agua) wrote:

>Hi With Plot[( (2x+1) Sqrt[x+1] ) / Sqrt[x-1] ,{x,-5,5}] hoped to
>obtain a graph only for x>1.

>What happened? regards.

There is a singularity at x = 1 and your expression isn't real
for -1 < x < 1. If you want to see more of the plot for x>1 add
specify the plot range to be greater. And if you only want to
see the plot for graph for x>1, set the range for x to start at
1. That is

Plot[( (2x+1) Sqrt[x+1] ) / Sqrt[x-1] ,{x,0,5}, PlotRange->{0,100}]

will only show the graph for x>1 and show more of that portion
of the graph.


From: David Park on 3 Jul 2010 08:16
I'm not certain of your question. Why don't you just do something like this:

Plot[((2 x + 1) Sqrt[x + 1])/Sqrt[x - 1], {x, 1, 5},
PlotRange -> {Full, {5, 20}},
Frame -> True]


David Park
djmpark(a)comcast.net
http://home.comcast.net/~djmpark/



From: agua [mailto:auguaylupo(a)gmail.com]


Hi
With Plot[( (2x+1) Sqrt[x+1] ) / Sqrt[x-1] ,{x,-5,5}]
hoped to obtain a graph only for x>1.

What happened?
regards.



From: Peter Pein on 3 Jul 2010 08:18
Am Fri, 2 Jul 2010 11:26:08 +0000 (UTC)
schrieb Sunt <sunting.05(a)gmail.com>:

> On Jul 2, 2:57 pm, agua <auguayl...(a)gmail.com> wrote:
> > Hi
> > With Plot[( (2x+1) Sqrt[x+1] ) / Sqrt[x-1] ,{x,-5,5}]
> > hoped to obtain a graph only for x>1.
> >
> > What happened?
> > regards.
>
> Hi,
> Add PlotRange option in the command Plot like:
> Plot[( (2x+1) Sqrt[x+1] ) / Sqrt[x-1] ,{x,-5,5},PlotRange->{1,100}]
>

or simply type Plot[...,{x,1,5}].

Plot plots whenever the expression to plot is real valued. Use
Mathematica to see that for real x your expression is real valued iff
x<=-1, x==-1/2 or x>1:

In[1]:= Reduce[Im[((2x+1) Sqrt[x+1])/Sqrt[x-1]]==0==Im[x],x]
Out[1]= x<=-1||x==-(1/2)||x>1

P=C2=B2


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