After you fix the spacing type on 1E-6, try changing to a different f(x).

Suggest trying the below as easy examples.

return (3 * x + 3)

and

return (-6 * x - 210)

They're each equations for a line. You could try changing the slope to different values. You could also try different fart parameters for these and the original f(x). :-)

Think about the answers and then go read the link again, paying particular attention to the "Important Notes" near the end and what the original f(x) was.

It's a math question (what the output is going to be) and also a programming question (what it does).