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There is the hold option, which might can help:

 z(x)=x.power(2).mul(x,hold=true)
 view(z)

which evaluates to $x \mapsto x^2x$ For an easier typing one could use Infix opertors:

 def hold_mult(a,b):
     return a.mul(b,hold=true)
 h = infix_operator('multiply')(hold_mult)

and then use x^2 *h* x.

However in your case if you need just the initial equation to display it might be the easiest just to print it as a string. If you need this functionality more often, an (extendet version of a) function like this could be helpful:

def paranthese_match(prefix,str):
   matches = []
   while (str.find(prefix) != -1):
       p = -1
       for li in [str.find(prefix)+len(prefix)..len(str)-1]:
           if str[li] == '(':
             p -=1
           if str[li] == ')':
             p += 1
           if p==0:
              matches.append(str[str.find(prefix)+len(prefix):li])
       str = str[li:]
   return matches
def print_expression(str):
   str = str.replace('*',' \cdot ')
   str = str.replace('pi',' \pi ')
   for sr in paranthese_match('sqrt(',str):
       str = str.replace('sqrt('+sr+")",'\sqrt{'+sr+'}')
   for sr in paranthese_match('exp(',str):
       str = str.replace('exp('+sr+")",'e^{'+sr+'}')
   html("$"+str+"$")

Then print_expresion("6/(5*pi*h*50*h*(x^2+25))*h*exp((-x+sqrt(x^2+25))/50)") leads to $6/(5 \cdot \pi \cdot h \cdot 50 \cdot h \cdot (x^2+25)) \cdot h \cdot e^{(-x+\sqrt{x^2+25})/50}$