Square Roots & Cube Roots
Aligned to 8.EE.A.2 — Common Core State Standards for Mathematics.
What this lesson teaches
√p answers "what number squared equals p?" and ∛p answers "what number cubed equals p?" Solving x^2 = p gives x = ±√p (two solutions); solving x^3 = p gives x = ∛p (one solution).
Worked example
Solve x^2 = 49. Take the square root of both sides: x = ±√49 = ±7, so x = 7 or x = −7. For x^3 = 27, x = ∛27 = 3, since 3 × 3 × 3 = 27.
Practice questions
- Evaluate √81.
- Solve x^2 = 144.
- Solve x^3 = 125 and explain why it has only one real solution.
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
Raíces Cuadradas y Cúbicas
√p responde "¿qué número al cuadrado da p?" y ∛p responde "¿qué número al cubo da p?" Resolver x^2 = p da x = ±√p (dos soluciones); resolver x^3 = p da x = ∛p (una solución).
Ejemplo: Resuelve x^2 = 49. Saca la raíz cuadrada de ambos lados: x = ±√49 = ±7, así que x = 7 o x = −7. Para x^3 = 27, x = ∛27 = 3, porque 3 × 3 × 3 = 27.
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