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Segundas Diferencias

Un patrón donde las diferencias entre términos consecutivos forman su propia secuencia aritmética.

Aprender

Un patrón donde las diferencias entre términos consecutivos forman su propia secuencia aritmética.

Second differences occur when the first differences between terms aren't constant, but the differences of those differences (second differences) are constant. This indicates a quadratic relationship. Sequences with constant second differences include square numbers, triangular numbers, and other polynomial sequences of degree 2.

If second differences are constant = c, then aₙ = An² + Bn + C

  • 1, 4, 9, 16, 25... (squares) → 1st diff: 3, 5, 7, 9 → 2nd diff: 2, 2, 2
  • 1, 3, 6, 10, 15... (triangular) → 1st diff: 2, 3, 4, 5 → 2nd diff: 1, 1, 1
  • 2, 6, 12, 20, 30... → 1st diff: 4, 6, 8, 10 → 2nd diff: 2, 2, 2

Cómo reconocerlo

  • Calculate first differences between consecutive terms
  • If first differences aren't constant, calculate second differences
  • Constant second differences indicate a quadratic pattern
  • The sequence grows faster than arithmetic but slower than geometric

Errores comunes

  • Stopping at first differences when they're not constant
  • Confusing with geometric sequences (check ratios vs differences)
  • Forgetting to continue to third differences for cubic sequences

Resolución paso a paso

Encuentra el siguiente término: 1, 3, 6, 10, 15, ?

  1. Calcula primeras diferencias: 3-1=2, 6-3=3, 10-6=4, 15-10=5
  2. Las primeras diferencias aumentan en 1 cada vez
  3. Segundas diferencias: 3-2=1, 4-3=1, 5-4=1
  4. Siguiente 1.ª dif = 6, así que siguiente término = 15 + 6 = 21

Respuesta: 21

Orientación para practicar

Secuencias Numéricas

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