Which method is better?

Factoring is faster when it works; the quadratic formula works for every quadratic.

What if the discriminant is negative?

There are no real roots in the current school-math calculator.

用因式分解和求根公式求解二次方程的解题示例。

使用这些示例来比较因式分解与求根公式在常见高中代数问题中的应用。

x = (-b +/- sqrt(b^2 - 4ac)) / (2a)。

题目: x^2 - 5x + 6 = 0

解答: (x - 2)(x - 3) = 0，所以 x = 2 或 x = 3。

题目: 2x^2 + x - 3 = 0

解答: 判别式为 25，所以 x = 1 或 x = -3/2。