Aprender
Una secuencia en la que cada término se obtiene multiplicando el anterior por una constante (razón común).
A geometric sequence (also called geometric progression) is a sequence where each term is obtained by multiplying the previous term by a fixed number called the 'common ratio'. Geometric sequences model exponential growth and decay, compound interest, population growth, and many natural phenomena.
aₙ = a₁ × rⁿ⁻¹, where r is the common ratio
- 2, 6, 18, 54, 162... (common ratio = ×3)
- 1000, 500, 250, 125... (common ratio = ×0.5 or ÷2)
- 1, -2, 4, -8, 16... (common ratio = ×(-2))
Cómo reconocerlo
- Divide each term by the previous term
- If all ratios are the same, it's geometric
- The pattern is 'multiply by the same number each time'
Errores comunes
- Confusing with arithmetic sequences (add vs multiply)
- Forgetting that division is multiplication by a fraction
- Missing negative ratios that cause alternating signs
Resolución paso a paso
Encuentra el siguiente término: 2, 6, 18, 54, ?
- Calcula las razones: 6÷2=3, 18÷6=3, 54÷18=3
- Todas las razones son iguales: razón común = 3
- Es geométrica. Multiplica el último término por 3
- El siguiente término es 162
Respuesta: 162