In your print equation (y equals the fraction “negative 1 over 3” x-squared minus 2x minus 3), since the fraction includes something other than “digits, decimal points, commas or separator spaces” (GTM 6.1), it cannot be a “simple numeric fraction.” So, for this fraction in which the numerator and denominator are on different levels in print, we must use the general fraction indicators and general fraction line. I would transcribe the whole equation as follows.
⠰⠽⠀⠐⠶⠀⠰⠷⠐⠤⠼⠁⠨⠌⠼⠉⠾⠭⠔⠼⠃⠐⠤⠼⠃⠭⠐⠤⠼⠉
Thank you for the question!
–Kyle