A1 = 1/3
D = -1/4
A н-нное =А1 + D * (н- нное -1)
А6 = 1/3 + (-1/4 * 5 ) = 1/3 - 5/4 = 4/12 - 15/12 = -17/12 = -1 ,5/12
А5 = 1/3 + -1/4*4 = 1/3 - 1 = -2/3
A9 = 1/3 + -1/4 *8 = 1/3 -2 = - 5/3 = -1 , 2/3
A11 =1/3 + -1/4 *10 = 1/3 - 10/4 = 4/12 - 30/12 = -16/12 = -4/3 = - 1 , 1/3
ОТВЕТ : Б