def extremum (a, b, c) -> tuple:
	""" Returns the (x, y) coordinates of the extremum of the curve given by the polynomial, f(x | a, b, c).
	The extremum can refer to either a maximum or minimum value.  When 'a' is negative, the max or top of the curve is returned.  Otherwise, the min is returned.
	The value of the x-coordinate can be thought of as the midpoint of the curve."""
	# Check params.
	if a == 0:
		raise ValueError('Argument Value Error:\tThe parameter, \'a\', in a polynomial, f(x) = ax^2 + bx + c, cannot be equal to zero.')
	x = -b/(2*a)
	return (x, a*x**2 + b*x + c)