How to Use the Discriminant to Determine Quadratic Solutions

The Organic Chemistry Tutor

This instructional math video provides a clear, step-by-step guide on how to use the discriminant to determine the nature of solutions for quadratic equations. The narrator introduces the specific rules associated with the discriminant value: positive values yield two real solutions, zero yields one real solution, and negative values yield two imaginary solutions. The video moves from theoretical definitions to practical application using the standard quadratic form. The content focuses on three primary examples that cover every possible outcome. The narrator walks through substituting coefficients into the formula $b^2 - 4ac$, performing the arithmetic, and interpreting the final result. Key concepts include identifying coefficients ($a$, $b$, and $c$), understanding the distinction between real and imaginary numbers, and recognizing perfect square trinomials. For educators, this video serves as an excellent direct instruction tool or review resource for Algebra I and II classes. It isolates the specific skill of analyzing the discriminant without getting bogged down in the full quadratic formula, allowing students to build intuition about polynomial behavior. It is particularly useful for scaffolding lessons on complex numbers or connecting algebraic solutions to graphical features like x-intercepts.