Пошаговое объяснение:
(n+2)!((n+3)(n+4)-1)
lim --------------------------- = 'сократим (n+2)! '
x->∞ (n+2)!(n+3)
(n+3)(n+4)-1
=lim --------------------------- =
x->∞ (n+3)
n²+7n+12-1
=lim -------------------- =
x->∞ (n+3)
n²+7n+11
=lim -------------------- =
x->∞ (n+3)
n( n+7+1/n)
=lim -------------------- = ' сократим на n ; 1/n, 3/n ->0
x->∞ n(1+3/n)
n+7
=lim -------------------- = ∞
x->∞ 1
б)
