TITLE: Is there a symbol for plus and minus as opposed to plus or minus?
QUESTION [17 upvotes]: I know that you can use $\pm$ for when the answer could be either positive or negative, e.g., $x^2=16$, $x=\pm 4$.
But is there a symbol that implies that you use both the positive and the negative values?  For example, I want to do something along the lines of:
$$(2/3a) \left(\sqrt[3]{2b^3 - 9abc + \sqrt{−4(b^2−3a)}} + \sqrt[3]{2b^3 - 9abc - \sqrt{−4(b^2−3a)}}\right)$$
It would be very useful to not have to write out the cube root twice and instead have a plus and minus sign before the square root.

REPLY [11 votes]: No, and there's a good reason for it: it cannot convey the necessary information.
How would the reader know that the intention is to add?
What if you intended the "and" to be for multiplication?
You need to denote the operator somehow, and that will take care of the "and" part by itself.