I've a question that generates a negative index for an assigned function and then displays it as outlined below:

Question Variables:

a0:rand(9)+1; a:a0*(-1); f(x):=x^a;

Question text:

Find the gradient function \[y'={@f(x)@}\].

This results in:

is there a way to force it to display the negative index (see below for desired result) without resorting to manually entering the function into the Question text

*Question-level simplify = "No"* doesn't fix it:

Thanks in advance,

Mike