Christmaths carols II

The Cubic and Quadratic (to the tune of The Holly and the Ivy)

The cubic and quadratic
Though they are both well known
Of all the functions that are in the book
Quadratic bears the crown.
Oh, the formula quadratic
And the solving for real roots
Whether there are two, one, or none (at all)
The discriminant will tell.
The cubic bears an index
Of three, its highest power
Quadratic bore exponent two
To be its sweet flavour.
The cubic bears a wiggle
As local max and min
Quadratic bore the zeros of
The first derivative.