Why is the supremum this? $M=\{y\in \mathbb R |y=3x+10:x\in(9,14)\}$
From what I've learned, this means
$9<x<14$?
DEF: Supremum
A figure $u\in \mathbb R$ so


*

*$a\leq u$ for all $a\in A$

*for all $\epsilon>0$ there exists such $a\in A$ so $u-\epsilon<a$


How come 52 is said to be the supremum..? I would like to say that 49 is.
Sorry for the bad layout - I don't really know how to use LaTeX

Remember that $x$ doesn't have to be an integer! For example, take $x=13.9999$. Then $y=3x+10$ will be very very close to $52$ (specifically, $51.9997$).
