Question

Найдите 17 член арифметической прогрессии -12;-6

Answer 1

An=-12;-6;...
a1=-12
d=an+1-an= -6-12=-18
a17= a1+d(17-1)
a17= -12-18*18= -12-324=-336

Answer 2

A1-(-12)
a2-(-6)
d=a2-a1=-6-(-12)=6
S17=96