code: function(c, b, a,  plus_or_min) { 
          var plus_or_minus = plus_or_min === '-' ? 'subtract': 'add';
          var bsqmin4ac = _.subtract(_.pow(b.clone(), Symbol(2)), _.multiply(_.multiply(a.clone(), c.clone()),Symbol(4)))/*b^2 - 4ac*/; 
          var det = _.pow(bsqmin4ac, Symbol(0.5));
          var retval = _.divide(_[plus_or_minus](b.clone().negate(), det),_.multiply(new Symbol(2), a.clone()));
          return retval;
      }
docs: solve quad oder polynomials symbolically