Are you using Mathematica to plot it or Wolfram|Alpha?
Square brackets are used for function application in Mathematica. The first step is to get your example into valid code. I'm not sure how to read the notation above. Maybe if you don't know the proper Wolfram Language syntax, you can provide the syntax in TeX?
Try typing out the functions with basic, unformatted code. Try to not use subscripts. Just use latin characters.
