Respuesta :

mhanifa

Answer:

-288

Step-by-step explanation:

Given AP

  • t(n) = 3 - 2n

To find,

  • The sum of first 18 terms

Solution

  • Sn = 1/2n(t(1) + t(n))

The first and 18th terms as per the formula

  • t(1) = 3 - 2 = 1
  • t(18) = 3 - 18*2 = 3 - 36 = -33
  • S18 = 1/2*18(1 - 33) = 9*(-32) = -288

Answer is -288

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