How to use operators without other symbol in a formula (Writer)

My problem: I want to add this kind of formula into my LibreOffice writer document: image description

What I have for now in my formula is: C = C({ Y-T }csub{ + }, i csub{ - })

But the operators like + or - can only be used with other characters. For example C = C( {Y-T}csub{ +0 }, i csub{-0})

My question is then: How to allow the usage of different operators (like + or -) in a formula without adding other character to see a result as on the image ?
(I tried using spaces, but it doesn’t work)


enclose operators in double quotes if you want to show the character only:

C = C({ Y-T } csub { "+" }, i csub { "-" })

To enlarge the character size you may want to use something like:

C = C({ Y-T } csub{ size 12 "+" }, i csub { size 12 "-" })

Hope that helps

Thank you very much!! that is the right answer.