[R] solve scalar linear equation

[message]

On 2014-05-20 10:00, r-help-request at r-project.org wrote:
> ------------------------------
> 
> Message: 32
> Date: Mon, 19 May 2014 23:04:27 +0100
> From: Rui Barradas <ruipbarradas at sapo.pt>
> To: message <letter at openmailbox.org>, r-help at r-project.org
> 
> uniroot(function(x) 5*x - 55, c(0, 20))
> 

Why does this instruction fail if the interval is changed?

> uniroot(function(x) 5*x - 55, c(0, 10))
Error in uniroot(function(x) 5 * x - 55, c(0, 10)) :
   f() values at end points not of opposite sign