Rewriting Expressions (Completing the Square)
Aligned to A-SSE.B.3 — Common Core State Standards for Mathematics.
What this lesson teaches
Equivalent forms of an expression reveal different information. Completing the square rewrites a quadratic to expose its vertex (maximum or minimum).
Worked example
x² + 6x + 5 = (x+3)² − 4. The vertex form shows a minimum at (−3, −4).
Practice questions
- Complete the square for x² + 4x.
- What does vertex form tell you that standard form hides?
- Rewrite x² + 8x + 10 in vertex form.
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Reescritura de Expresiones (Completar el Cuadrado)
Las formas equivalentes de una expresión revelan información diferente. Completar el cuadrado reescribe una expresión cuadrática para mostrar su vértice (máximo o mínimo).
Ejemplo: x² + 6x + 5 = (x+3)² − 4. La forma de vértice muestra un mínimo en (−3, −4).
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