Question

Write the given interval in set-builder form: [-23, 5]

Answer 1

first of all, you should understand how to write in set - builder form ?
this can be understand easily with help of a beautiful example. 
Let's consider a set A = {1, 2, 3, 4.. 8} 
we have to write in set - builder form.
so, we should write $A=\{x|x<9\:\text{and}\:x\in\mathbb{N}\}$
where The braces { } means " the set of " 
" x| " means " all numbers x such that " 
everything after the " | " describes that set.
so, in this case it means $\textbf{x is less than 9 and is a natural number}$.

now come to the question,
Here, the given interval = [-23, 5)

Now the set of values of any variable for given set is such that x is greater than - 23( including 23 as the bracket is closed) and less than 5 (as the bracket is open).
now, set builder form of the given interval can be written as follows: {x | x$\in\mathbb{R}$, -23 ≤ x < 5}