Question

Find the sum of the arithmetic series

Answer 1

• The sum is - 891

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Given AP with the nth term:

• 
  `t_n=-5n+37`

The number of terms is 27.

Sum of the first n terms is:

• 
  `S_(n)=(t_1+t_n)*n/2`

The first term is:

• 
  `t_1=-5*1+37=-5+37=32`

The 27th term is:

• 
  `t_(27)=-5*27+37=-98`

Sum of the first 27 terms is:

• 
  `S_(27)=(32+(-98))*27/2=-66*27/2=-891`