Taking input as f(x) into graphing calculator

Questions
1

I am having trouble with slide 4 on my activity Graphs of Logarithms - Lesson 17 Day 2 • Activity Builder by Desmos

I want the students to be able to input f(x) = 5^x. The way I have it set up is so close to working. If I use y = as the initial text, it works. Later in the activity, they will be graphing f(x) and g(x) and comparing, so I don’t want to use y=notation.
I have tried using x, f. I’ve tried parsing into left and right sides. I just don’t understand it well enough to figure out how to fix it. Any help is appreciated!

2

Not sure if this is what you are looking for but here you go.
I prefer to parse the equation and then just use the right hand side (rhs).