I have a few functions that I'm trying test through the use of a class and I can't figure out how to show that I've set them up correctly

I.e.

my first function:

def f(x):

return 8 * x ** 2 + 3 * x

now if I wanted to test that, say with x=2 using self.assertEqual how would I set that up?

Any help is appreciated. Thanks:)