Question 394693: In the following example what does the [ mean and why are { } used after the = sign and why is the I between the two x's. [a,oo)= {xIx > a} (there is a line under the greater than sign, I do not know what the symbol means)
My name is Dolly and my email is elkm@suddenlink.net
Answer by jrfrunner(365)   (Show Source):
You can put this solution on YOUR website! In the following example what does the [ mean and why are { } used after the = sign and why is the I between the two x's. [a,oo)= {xIx > a} (there is a line under the greater than sign, I do not know what the symbol means)
My name is Dolly and my email is elkm@suddenlink.net
--
in mathematics (and many other disciplines), there are short hand or short cuts for saying something.
a "[" means that the value is included, a ")" means the value is not included
"{}" is a way to say the set of numbers
the "I" is really not an I, but a short line to imply the meaning "such that"
--
so [a,oo) means all values between a and infinity including a but since we do not know what infinity is it is left unincluded.
--
{xIx > a} this means the set of x numbers, such that x is greater than a.
of course this statement is wrong since they are trying to define [a,oo) which includes "a". So the statement should look as [a,oo)= {xIx >= a}, its missing teh equal sign to show that it includes "a"
|
|
|
