c1=-5, cn+1=cn-2
Найдите c7

c8 = c7 - 2c2 = c1 - 2 = -5 - 2 = -7c3 = c2 - 2 = -7 - 2 = -9c4 = c3 - 2 = -9 - 2 = -11c5 = c4 - 2 = -11 - 2 = -13c6 = c5 - 2 = -13 - 2 = -15c7 = c6 - 2 = -15 - 2 = -17____________________| c8 = c7 - 2 = -17 - 2 = -19 | Возможно так