please help, i dont know how to post on latex, for example the attachment is on the link below but I dont know how to post on this message
Just surround your code with [tex] and [/tex]. The board sets math mode automatically, so don't use dollar signs around everything.
For example:
ProducesCode:[tex]\sum_{n=1}^\infty\frac1n=\frac{\pi^2}6[/tex]
Use \text{} to get regular non-math text. There are limits on the number of characters and the size of each image, so you may need to break things up into several sections. For full paragraphs of text, like in your PDF, post the non-math text outside of the [tex] tags.
So, for the record, the actual question that the OP wants an answer for is:
l.u.b. = 5, g.l.b. = 1. Do you see why?Find the least upper bound and the greatest lower bound of the following sets. For a given >0, find a number in the set that exceeds (l.u.b.A)- and a number in the set that is smaller than (g.l.b. A)+ .