Mathematics for IGCSE & O level - Equations (Section 4 - No. 14)
Which is the appropriate situation to use the quadratic formula?
When you can easily factor a quadratic.
When it is not possible to factor a quadratic.
When the equation has only one variable.
When you want to simplify the quadratic.
Forklaring
The quadratic formula works regardless of whether the equation can be easily factored or not.