Вынесите общий множитель за скобки -m²n+5mn²-6m²n²И(х-1)²+7(х-1)

185. а1=103, d = -2

а) S(n) = (2a1+d(n-1))*n/2. Тогда:

S(8) = (206 - 14)*8/2 = 768

б) S(103) = (206 - 204)*103/2 = 103

186.

 а)А₁=7,d=4, n=13;

a(n) = a(1)+d(n-1) = 7+4n-4 = 4n+3 = 55

S(n) = (14+4(n-1))*n/2 = 403

б)А₁=2,d=2,n=40;

A(n) = 2+2*39 = 80;

S(n) = (4+2*39)*40/2 = 1640

в)A₁=56,d=-3,n=11

A(n) = 56 - 3*10 = 26

S(n) = (112-3*10)*11/2= 451

188.  Y1= -32,  d = 5

a) S(10) = (-64 + 5*9)*10/2 = -95

б) S(26) = (-64 + 5*25)*26/2 = 793

189. a1 = 25,  d = -4,5

a) S(16) = (50-4,5*15)*16/2 = - 140

б) S(40) = (50 - 4,5*39)*40/2 = - 2510