// d/dx(u/v) = 1/v du/dx - u/v2 dv/dx public override MathElement Derive() => new SumElement( new ProductElement( new FractionElement( new ConstElement(1, IsNegative), Denominator), Numerator.Derive()), new ProductElement( !IsNegative, new FractionElement( Numerator, new PowerElement( Denominator, new ConstElement(2))), Denominator.Derive()));