Linear equation

For ax + b = 0, the root is x = -b/a. This mode solves equations with one unknown and one root.

Quadratic equation

For ax^2 + bx + c = 0, roots are based on the discriminant D = b^2 - 4ac. Positive D gives two real roots, zero gives one repeated root, and negative D gives complex roots.

驗證

Coefficient A cannot be zero in both modes because that would remove the highest-degree term and change the equation type.