What can I use as a Plus or Minus sign?

In this equation I can't figure out how to make the + into a plus or minus sign to get both answers other than doing it twice with s1 and s2 instead of s.

s=(-800/(2*.1))+(sqrt(((800/(.1*2))^2)-(1/(.1*.000001))));

Answer 1

[Joseph Cheng]

s=(-800/(2*.1))+[1 -1]*(sqrt(((800/(.1*2))^2)-(1/(.1*.000001))))