A pale purple colour is generally known as 'lilac' after the bush.
Purple lilac: Syringa vulgaris
Larger lilac cultivar image
Cordate leaves of Syringa vulgaris
... square roots of both sides yields <math>x+\frac{b}{2a}=\frac{\pm\sqrt{b^2-4ac}}{2a}.</math> Subtracting b/(2a) from both ...