A) 2x+4≠0 2x≠-4 x≠-2
D(y)=(-∞;-2)U(-2;+∞)
b) (4+x)(x-2)≠0 4+x≠0 x≠-4 x-2≠0 x<span>≠2
D(y)= (-</span>∞; -4)U(-4;2)U(2;+<span>∞</span>)
D=a2–a1=81,1–85,6=–4,5
an=a1+d(n–1)=85,6–4,5n+4,5=
= 90,1–4,5n
90,1–4,5n>0
–4,5n>–90,1
n<20,022
Ответ: 20 членов данной прогрессии положительны