Respuesta :

mhanifa

Answer:

Sum of n terms of a GP:

  • Sₙ = a₁(rⁿ - 1)/(r - 1)

#1

  • a₁ = 5
  • r = 2
  • n = 9
  • S₉ = 5(2⁹ - 1)/(2 - 1) = 5(511) = 2555

Correct choice is C

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#2

  • a₁ = 12
  • r = 1/2
  • n = 5
  • S₅ = 12(1 - (1/2)⁵)/(1 - 1/2) = 12(31/32)/(1/2) = 23.25

Correct choice is A