Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: Logs
Replies: 4   Last Post: Oct 15, 2013 12:42 AM

 Messages: [ Previous | Next ]
 William Elliot Posts: 2,637 Registered: 1/8/12
Re: Logs
Posted: Oct 14, 2013 11:55 PM

On Mon, 14 Oct 2013, Virgil wrote:
> William Elliot <marsh@panix.com> wrote:
> > On Mon, 14 Oct 2013, gyansorova@gmail.com wrote:
> >

> > > If x and y are both positive can we ever approximate
> > > log(x+y) := log(x) + log(y)
> > >

> > x + y = e^log(x + y) = e^(log x + log y) = e^log x * e^log y = xy.
> > Can you ever approximate xy = x + y?

>
> For x =/= 1, one can find y exactly, and for y =/= 1,
> one can find x exactly, no approximating needed

0 = x - xy + y = -(x - 1)(y - 1) + 1

Date Subject Author
10/14/13 gyansorova@gmail.com
10/14/13 William Elliot
10/14/13 Virgil
10/14/13 William Elliot
10/15/13 Virgil