bodhiclassesKnow which method to use—and why—before you start calculating.
Quadratic Equations: lesson notes
A quadratic equation has highest power two and can be written in the form ax² + bx + c = 0.
Start by checking whether the expression factorises cleanly. If it does not, use the quadratic formula. Completing the square is especially useful when you want to understand the graph and vertex.
Always substitute your roots back into the original equation. This final check catches sign errors quickly.