When you input a value of x into the function f, you evaluate the expression −5x+8 to get the corresponding output.
The function you provided is a quadratic function, and you can represent it using function notation as follows:

In this notation:
f is the name of the function.
x is the input variable.
f(x) represents the output of the function when the input is x.
So, when you input a value of x into the function f, you evaluate the expression −5x+8 to get the corresponding output.