Re: DSolving(?) for a given tangent
- To: mathgroup at smc.vnet.net
- Subject: [mg81385] Re: [mg81358] DSolving(?) for a given tangent
- From: DrMajorBob <drmajorbob at bigfoot.com>
- Date: Fri, 21 Sep 2007 03:10:51 -0400 (EDT)
- References: <29733598.1190315398568.JavaMail.root@m35>
- Reply-to: drmajorbob at bigfoot.com
f[x_] := E^(0.22 x);
x45 = x /. FindRoot[f'[x] == 1, {x, 10}]
6.8824
or
f[x_] := E^(22 x/100);
x45 = x /. First@Quiet@Solve[f'[x] == 1, x]
50/11 Log[50/11]
and either way,
Plot[{f[x], f[x45] + x - x45}, {x, 0, 10}, Frame -> True,
AspectRatio -> Automatic,
Epilog -> {PointSize[0.02], Point[{x45, f@x45}],
Text[{x45, f@x45}, {x45 + 1, f@x45 - 2/3}]}]
Bobby
On Thu, 20 Sep 2007 02:53:19 -0500, AngleWyrm <anglewyrm at yahoo.com> wrote:
> Don't know for sure if this is the right function, so here's the
> scenario:
>
> f[x_] := E^(0.22 x);
> Plot[f[x], {x, 6, 36}]
>
> Which plots a nice escalating curve.
>
> What I would like to know is: Where is the point {x,f[x]} that has a
> 45-degree tangent line; ie where is this curve's balance point before it
> really starts taking off?
>
>
>
>
--
DrMajorBob at bigfoot.com